Diagnostic Trouble Code (DTC) Descriptions
DTC - Description Possible Causes Diagnostic Aides
P0102 - Mass Air Flow (MAF) Circuit Low Input
The MAF sensor circuit is monitored by the PCM for low air flow (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine running the air flow (or voltage) changes below a minimum calibrated limit, the test fails. MAF sensor disconnected
MAF circuit open to PCM
VPWR open to MAF sensor
PWR GND open to MAF sensor
MAF RTN circuit open to PCM
MAF circuit shorted to GND
Intake air leak (near MAF sensor)
A closed throttle indication [throttle position (TP) sensor system]
Damaged MAF sensor
Damaged PCM
A MAF V PID (MAF PID) reading less than 0.23 volts (Refer to equivalent grams/second chart in GO to Pinpoint Test DC ) in continuous memory or key ON and engine running indicates a hard fault.
P0103 - Mass Air Flow (MAF) Circuit High Input The MAF sensor circuit is monitored by the PCM for high air flow (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the air flow (or voltage) changes above a maximum calibrated limit, the test fails. MAF sensor screen is blocked
MAF circuit shorted to VPWR
Damaged MAF sensor
Damaged PCM
A MAF V PID (MAF PID) reading less than 4.6 volts (Refer to equivalent grams/second chart in GO to Pinpoint Test DC ) in continuous memory or key ON and engine running indicates a hard fault.
P0106 - Barometric (BARO) Pressure Sensor Circuit Performance Baro sensor input to the PCM is monitored and is not within the calibrated value. Slow responding BARO sensor
Electrical circuit failure
Damaged BARO sensor
Damaged PCM
VREF voltage should be between 4.0 and 6.0 volts
PID reading is in frequency
P0107 - BARO/MAP Sensor Low Voltage Detected Sensor operating voltage is less than 0.25 volts (VREF), as a result it failed below the minimum allowable calibrated parameter. Open in the circuit, or short to ground
VREF circuit open, or short to ground
Damaged BARO/MAP sensor
Damaged PCM
VREF should be greater than 4.0 volts
PID reading is in frequency/volts
P0108 - BARO/MAP Sensor High Voltage Detected Sensor operating voltage is greater than 5.0 volts (VREF), as a result it failed above maximum allowable calibrated parameter. VREF shorted to VWPR
BARO/MAP signal shorted to VPWR
Damaged BARO/MAP sensor
Damaged PCM
VREF should be less than 6.0 volts. PID reading is in frequency/Volts
P0109 - BARO/MAP Sensor Circuit Intermittent The sensor signal to the PCM is failing intermittently. Loose electrical connection
Damaged BARO/MAP sensor
Check harness and connection.
P0112 - Intake Air Temperature (IAT) Circuit Low Input Indicates the sensor signal is less than Self-Test minimum. The IAT sensor minimum is 0.2 volts or 121°C (250°F). Grounded circuit in harness
Damaged sensor
Improper harness connection
Damaged PCM
IAT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0113 - Intake Air Temperature (IAT) Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The IAT sensor maximum is 4.6 volts or -50°C (-58°F). Open circuit in harness
Sensor signal short to power
Damaged sensor
Improper harness connection
Damaged PCM
IAT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0116 - Engine Coolant Temperature Circuit Range/Performance Failure Indicates the engine coolant temperature rationality test has failed. The PCM logic that sets this DTC indicates that engine coolant temperature sensor (ECT or CHT) drifted higher than the nominal sensor calibration curve and could prevent one or more OBD II monitors from executing.
The PCM runs this logic after an engine off "calibrated soak period (typically 6 hours). This soak period allows the Intake Air Temperature (IAT) and engine coolant temperature (CHTor ECT) to stabilize and not differ by more than a calibrated value. DTC P0116 is set when all of the following conditions are met:
Engine coolant temperature at engine start exceeds IAT at engine start by more than a calibrated value, typically 30°F (1°C).
Engine coolant temperature exceeds a calibrated value, typically 225F (107C).
The Fuel, Heated Oxygen Sensor, Catalyst and Misfire monitors have not completed.
Calibrated timer to set DTC P0116 has expired.
Engine Coolant Temperature (ECT) or Cylinder Head Temperature (CHT) sensor
Coolant System Concern
Ensure IAT and engine coolant temperature are similar when engine is cold. Also ensure engine coolant temperature sensor (ECT or CHT) and actual engine operating temperature are the same.
P0117 - Engine Coolant Temperature (ECT) Circuit Low Input Indicates the sensor signal is less than Self-Test minimum. The ECT sensor minimum is 0.2 volts or 121°C (250°F). Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC. Grounded circuit in harness
Damaged sensor
Improper harness connection
Damaged PCM
ECT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0118 - Engine Coolant Temperature (ECT) Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The ECT sensor maximum is 4.6 volts or -50°C (-58°F). Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC. Open circuit in harness
Sensor signal short to power
Damaged PCM
Improper harness connection
Damaged sensor
ECT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0121 - Throttle Position (TP) Circuit Performance Problem The TP sensor circuit is monitored by the PCM for a non closed throttle position at idle. If key ON engine running self-test terminates upon placing the transmission range selector in gear (DRIVE or REVERSE) or when closing the throttle (idle) after opening it (in PARK or NEUTRAL) the TP closed throttle position is not attained, the test fails. Binding throttle linkage
Damaged throttle body
TP circuit open to PCM
Damaged TP sensor
SIG RTN circuit open to TP sensor
Drive vehicle, bring to a stop, turn key OFF. Start vehicle, run key ON engine running self-test at idle. Access KOER diagnostic trouble codes on scan tool.
P0122 - Throttle Position (TP) Circuit Low Input The TP sensor circuit is monitored by the PCM for a low TP rotation angle (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) changes below a minimum calibrated limit, the test fails. TP sensor not seated properly
TP circuit open to PCM
VREF open to TP sensor
TP circuit short to GND
Damaged TP sensor
Damaged PCM
A TP PID (TP V PID) reading less than 3.42% (0.17 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.
P0123 - Throttle Position (TP) Circuit High Input The TP sensor circuit is monitored by the PCM for a high TP rotation angle (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) changes above maximum calibrated limit, the test fails. TP sensor not seated properly
TP circuit short to PWR
VREF short to PWR
SIG RTN circuit open to TP sensor
Damaged TP sensor
Damaged PCM
A TP PID (TP V PID) reading greater than 93% (4.65 volts) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.
P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control Indicates the ECT or CHT sensor has not achieved the required temperature level to enter closed loop operating conditions within a specified amount of time after starting engine. Insufficient warm up time
Low engine coolant level
Leaking or stuck open thermostat
Malfunctioning ECT sensor
Malfunctioning CHT sensor
Refer to Thermostat Monitor in Section 1, Description and Operation, for system information.
P0127 - Intake Air Temperature Too High Indicates that IAT2 sensor has detected a potential abnormality in the intercooler system. This condition will cause the boost from the supercharger to be bypassed to avoid potential engine damage. Blockage of heat exchangers
Low fluid level
Fluid leakage
Intercooler pump or relay failure
Crossed intercooler coolant lines
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P0131 - HO2S Sensor Circuit Out of Range Low Voltage (HO2S-11) The HO2S sensor is monitored for a negative voltage known as characteristic shift downward (CSD). If the sensor is thought to be switching from 0 volts to -1 volts during testing, the PCM will use this input and remain in fuel control. Contaminated HO2S (water, fuel, etc)
Crossed HO2S signal/signal return wiring
P0133 - HO2S Sensor Circuit Slow Response (HO2S-11) The HEGO Monitor checks the HO2S Sensor frequency and amplitude. If during testing the frequency and amplitude were to fall below a calibrated limit, the test will fail. Contaminated HO2S sensor.
Exhaust leaks.
Shorted /open wiring.
Improper fueling.
MAF sensor.
Deteriorating HO2S sensor.
Inlet air leaks.
Access HO2S test results from the Generic OBD-II menu to verify DTC.
P0135 - HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S.
Water in harness connector.
Open VPWR circuit.
Open GND circuit.
Low battery voltage.
Corrosion or poor mating terminals and wiring
Damaged HO2S heater.
Damaged PCM.
Wiring.
Damaged HO2S heater.
Damaged PCM.
P0136 - HO2S Sensor Circuit Malfunction (HO2S-12) The downstream HO2S sensor(s) are continuously checked for maximum and minimum voltages. The test fails when the voltages fail to meet the calibrated limits. Pinched, shorted, and corroded wiring and pins.
Crossed sensor wires.
Exhaust leaks.
Contaminated or damaged sensor.
P0141 - HO2S Sensor Circuit Malfunction (HO2S-125) See DTC P0135
P0148 - Fuel Delivery Error At least one bank lean at wide open throttle. Severely restricted fuel filter.
Severely restricted fuel supply line.
P0151 - HO2S Sensor Circuit Out of Range Low Voltage (HO2S-21) See DTC P0131
P0153 - HO2S Sensor Circuit Slow Response (HO2S-21) See DTC P0133
P0155 - HO2S Sensor Circuit Malfunction (HO2S-21) See DTC P0135
P0156 - HO2S Sensor Circuit Malfunction (HO2S-22) See DTC P0136
P0161 - HO2S Sensor Circuit Malfunction (HO2S-22) See DTC P0135
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:
Fuel system
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Induction system:
Air leaks after the MAF.
Vacuum Leaks.
PCV system.
Improperly seated engine oil dipstick.
EGR system:
Leaking gasket.
Stuck EGR valve.
Leaking diaphragm or EVR.
Base Engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
A SHRTFT-1,2 PID value between -25% to +35% and a LONGFT-1,2 PID value between -35% to +35% is acceptable. Reading beyond these values indicate a failure.
P0172 - System to Rich (Bank 1) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit. See Possible Causes for DTC P0171 See Diagnostic Aides for DTC P0171
P0174 - System to Lean (Bank 2) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. See Possible Causes for DTC P0171. See Diagnostic Aides for DTC P0171
P0175 - System to Rich (Bank 2) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit. See Possible Causes for DTC P0171. See Diagnostic Aides for DTC P0171
P0176 - Flexible Fuel (FF) Sensor Circuit Malfunction The FF sensor input signal to PCM is continuously monitored. The test fails when the signal falls out of a maximum or minimum calibrated range. Open or short in FF sensor VPWR circuit
Open in battery ground to FF sensor circuit
Open in FF sensor signal circuit
Short to ground in FF sensor signal circuit
Fuel contamination
Short to VPWR in FF sensor battery ground circuit
Short to VPWR in FF sensor signal circuit
Fuel separation
Damaged FF sensor
Damaged PCM
A flex fuel (FF) PID reading of 0 Hz with the key ON and engine OFF or with engine at idle indicates a hard fault.
P0180 - Engine Fuel Temperature Sensor A Circuit Low Input (EFT) The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for low and high voltage. If voltage were to fall below or exceed a calibrated limit and amount of time during testing, the test will fail. Open or short in harness.
Low ambient temperature operation.
Improper harness connection.
Damaged EFT sensor.
Damaged PCM.
Verify EFT-PID value to determine open or short.
P0181 - Engine Fuel Temperature Sensor A Circuit Range/ Performance (EFT) The comprehensive component monitor (CCM) monitors the EFT Temperature for acceptable operating temperature. If during testing voltage were to fall below or exceed a calibrated limit, a calibrated amount of time the test will fail. Open or short in harness.
Low ambient temperature operation.
Improper harness connection.
Damaged EFT sensor.
Damaged PCM.
Verify EFT-PID value to determine open or short.
P0182 - Engine Fuel Temperature Sensor A Circuit Low Input (EFT) The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for low voltage. If voltage were to fall below a calibrated limit and amount of time during testing, the test will fail. Short in harness.
VREF open or shorted.
Low ambient temperature operation.
Improper harness connection.
Damaged EFT sensor.
Damaged PCM.
Verify EFT-PID and VREF values to determine open or short.
P0183 - Engine Fuel Temperature Sensor A Circuit High Input (EFT) The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for high voltage. If voltage were to exceed a calibrated limit and a calibrated amount of time during testing, the test will fail. Open or short to PWR in harness.
Damaged EFT sensor.
Improper harness connection.
Damaged PCM.
Verify EFT-PID value to determine open or short.
P0186 - Engine Fuel Temperature Sensor B Circuit Range/Performance (EFT) See DTC P0181.
P0187 - Engine Fuel Temperature Sensor B Circuit Low Input (EFT). See DTC P0182.
P0188 - Engine Fuel Temperature Sensor B Circuit High Input (EFT) See DTC P0183.
P0190 - Fuel Rail Pressure Sensor Circuit Malfunction (FRP) The comprehensive component monitor (CCM) monitors the FRP sensor to the PCM for VREF voltage. The test fails when the VREF voltage from the PCM drops to a voltage less than a minimum calibrated value. VREF open in harness.
VREF open in sensor.
VREF open in PCM.
Verify VREF voltage between 4.0 and 6.0V.
P0191 - Fuel Rail Pressure Sensor Circuit Performance (FRP) The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below or exceeds a minimum/maximum calibrated value for a calibrated period of time. High fuel pressure.
Low fuel pressure.
Damaged FRP sensor.
Excessive resistance in circuit.
Low or no fuel.
A FRP PID value during KOER of 138 kpa (20 psi) and 413 kpa (60 psi) for gasoline or 586 kpa (85 psi) and 725 kpa (105 psi) for natural gas vehicles (NG) is acceptable.
P0192 - Fuel Rail Pressure Sensor Circuit Low Input (FRP) The comprehensive component monitor (CCM) monitors the FRP sensor circuit to the PCM for low voltage. If voltage were to fall below a calibrated limit and amount of time during testing, the test will fail. FRP signal shorted to SIG RTN or PWR GND.
FRP signal open (NG only)
Low fuel pressure (NG only)
Damaged FRP sensor.
Damaged PCM.
A FRP PID value during KOER or KOEO less than 0.3 volts for gasoline or 0.5 volts for natural gas vehicles (NG) would indicate a hard fault.
P0193 - Fuel Rail Pressure Sensor Circuit High Input (FRP) The comprehensive component monitor (CCM) monitors the FRP sensor circuit to the PCM for high voltage. If voltage were to fall below a calibrated limit and a calibrated amount of time during testing, the test will fail. FRP signal shorted to VREF or VPWR.
FRP signal open (gasoline only)
Low fuel pressure (NG only)
Damaged FRP sensor.
Damaged PCM.
High fuel pressure (caused by damaged fuel pressure regulator) NG.
A FRP PID value during KOER or KOEO less than 0.3 volts for gasoline or 0.5 volts for natural gas vehicles (NG) would indicate a hard fault.
P0201 through P0212 - Cylinder #1 through Cylinder #12 Injector Circuits The comprehensive component monitor (CCM) monitors the operation of the fuel injector drivers in the PCM. The test fails when the fuel injector does not operate electrically even though the harness assembly and fuel injectors test satisfactorily. Faulty fuel injector driver within the PCM.
PID Data Monitor INJ1F-INJ12F fault flags = YES.
P0217 - Engine Coolant Over-Temperature Condition Indicates an engine overheat condition was detected by the cylinder head temperature (CHT) sensor. This condition will cause the boost from the supercharger to be bypassed to avoid potential engine damage. Engine cooling system concerns.
Low engine coolant level.
Base engine concerns.
Monitor CHT PID for overheat condition. Typical CHT temperature should be close to cooling system thermostat opening specification.
P0230 - Fuel Pump Primary Circuit Malfunction NOTE: For natural gas applications, the following description applies to the fuel shutoff valve (FSV) circuit.
The PCM monitors the fuel pump (FP) circuit output from the PCM. The test fails if: With the FP output commanded ON (grounded), excessive current draw is detected on the FP circuit; or with the FP output commanded OFF, voltage is not detected on the FP circuit (the PCM expects to detect VPWR voltage coming through the fuel pump relay coil to the FP circuit). Open or shorted fuel pump (FP) circuit
Open VPWR circuit to fuel pump relay
Damaged fuel pump relay
Damaged PCM
When the FPF PID reads YES, a fault is currently present.
An open circuit or short to ground can only be detected with the fuel pump commanded OFF.
A short to power can only be detected with the fuel pump commanded ON.
During KOEO and KOER self-test, the fuel pump output command will be cycled ON and OFF.
P0231 - Fuel Pump Secondary Circuit Low NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits.
The PCM monitors the fuel pump monitor (FPM) circuit. The test fails if the PCM commands the fuel pump ON and B+ voltage is not detected on the FPM circuit. Open B+ circuit to the fuel pump relay
Open FP PWR circuit between the fuel pump relay and its connection to the FPM circuit
Damaged fuel pump relay
Damaged PCM (engine will start)
For 4.6L Mustang, open FP PWR circuit from low speed fuel pump relay, through resistor to FPM splice (engine will start)
For 5.4L SC Lightning, damaged IFS switch, IFS switch relay, or concern with related circuits.
During KOEO self-test, the PCM will command the fuel pump ON so this test can be performed.
P0232 - Fuel Pump Secondary Circuit High NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits.
The PCM monitors the fuel pump monitor (FPM) circuit. This test fails when the PCM detects voltage on the FPM circuit while the fuel pump is commanded OFF. The FPM circuit is wired to a pull-up voltage inside the PCM. The FPM circuit will go high if, with the key ON and the fuel pump commanded OFF, the FPM/FP PWR circuit loses its path to ground through the fuel pump. The FPM circuit will also go high if the FPM/FP PWR circuit is shorted to power.
Inertia fuel shutoff (IFS) switch not reset or electrically open
Open circuit between the fuel pump and the FPM connection to the FP PWR circuit
Poor fuel pump ground
Fuel pump electrically open
Fuel pump secondary circuits short to power
Fuel pump relay contacts always closed
Open FPM circuit between PCM and connection to FP PWR circuit
Damaged low speed fuel pump relay or concern with related circuits (if equipped).
Damaged PCM
Continuous memory P0232 can be set if the IFS switch was tripped, then reset, or if the fuel pump circuit is activated when the PCM expected the circuit to be off (i.e. fuel system test or prime procedure).
P0234 - Supercharger Overboost Condition The PCM disables (bypasses) the supercharger boost and sets a diagnostic trouble code (DTC) to keep from damaging the powertrain (engine or transmission) during potential harmful operating conditions. Brake torque (brake on and throttle at wide open)
Transmission oil temperature (TOT) exceeds calibrated threshold
Engine over temperature
Ignition misfire exceeds calibrated threshold
Knock sensor (KS) failure or knock detected
Low speed fuel pump relay not switching
Check for other diagnostic trouble codes accompanying the P0234 or check appropriate and available PIDs related to above possible causes.
P0243 - Supercharger (Boost) Bypass Solenoid Circuit Malfunction The PCM monitors the supercharger (boost) bypass (SCB) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified SCB solenoid duty cycle (100% or 0%) by PCM command. VPWR circuit open to SCB solenoid
SCB solenoid circuit shorted to PWR GND or CHASSIS GND
Damaged SCB solenoid
SCB solenoid circuit open
SCB solenoid circuit shorted to VPWR
Damaged PCM
Disconnect SCB solenoid. Connect test lamp to SCB solenoid harness connector. Cycle SCB driver in PCM by Output Test Mode. Test lamp cycle on and off - SCB solenoid is suspect. Test lamp always on - SCB signal short in harness or PCM. Test always off - SCB signal or VPWR open in harness or PCM.
P0298 - Engine Oil Over Temperature Condition Indicates the Engine Oil Temperature Protection strategy in the PCM has been activated. This will temporarily prohibit high engine speed operation by disabling injectors, therefore reducing the risk of engine damage from high engine oil temperature. Note: On engines which are equipped with an oil temperature sensor, the PCM reads oil temperature to determine if it is excessive. When an oil temperature sensor is not present, the PCM uses an oil algorithm to infer actual temperature. Engine shutdown strategy function is the same on vehicles with and without oil temperature sensors. Very high engine rpm for extended period of time.
Over-heating condition.
Malfunction EOT sensor or circuit (vehicles w/EOT sensor).
Base engine concerns.
Engine operating in high rpm range, due to improper gear selection. May cause Lack/Loss of Power or Surge customer concern.
P0300 - Random Misfire The random misfire DTC indicates multiple cylinders are misfiring or the PCM cannot identify which cylinder is misfiring. Camshaft position sensor (CMP)
Low fuel: less than 1/8 tank
Stuck open EGR valve
Blocked EGR passages
One or more EGR passages may be blocked or partially blocked. If this is the case the Misfire Detection Monitor will indicate the EGR port to check for possible blockage.
P0301 through P0310 - Misfire Detection Monitor The misfire detection monitor is designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. Ignition system
Fuel injectors
Running out of fuel
EVAP canister purge valve
Fuel pressure
Evaporative emission system
Base engine
The MIL will blink once per second when a misfire is detected severe enough to cause catalyst damage. If the MIL is on steady state, due to a misfire, this will indicate the threshold for emissions was exceeded and cause the vehicle to fail an inspection and maintenance tailpipe test.
P0320 - Ignition Engine Speed Input Circuit Malfunction The ignition engine speed sensor input signal to PCM is continuously monitored. The test fails when the signal indicates that two successive erratic profile ignition pickup (PIP) pulses have occurred. Loose wires/connectors.
Arcing secondary ignition components (coil, wires and plugs)
On board transmitter (2-way radio)
The DTC indicates that two successive erratic PIP pulses occurred.
P0325 - Knock Sensor 1 Circuit Malfunction (Bank 1) See DTC P0326
P0326 - Knock Sensor 1 Circuit Range/ Performance (Bank 1) The knock sensor detects vibrations upon increase and decrease in engine rpm. The knock sensor generates a voltage based on this vibration. Should this voltage go outside a calibrated level a DTC will set. Knock sensor circuit short to GND
Knock sensor circuit short to PWR
Knock sensor circuit open
Damaged knock sensor
Damaged PCM
A knock sensor voltage greater than 0.5V with the key ON and engine OFF indicates a hard fault.
P0330 - Knock Sensor 2 Circuit Malfunction (Bank 2) See DTC P0331
P0331 - Knock Sensor 2 Circuit Range/performance (Bank 2) The knock sensor detects vibration upon increase and decrease in engine rpm. The knock sensor generates a voltage based on this vibration. Should this voltage go outside a calibrated level a DTC will set. Knock sensor circuit short to GND
Knock sensor circuit short to PWR
Damaged knock sensor
Damaged PCM
Knock sensor circuit open
A knock sensor voltage greater than 0.5V with the key ON and engine OFF indicates a hard fault.
P0340 - Camshaft Position (CMP) Sensor Circuit Malfunction The test fails when the PCM can no longer detect the signal from the CMP sensor. CMP circuit open
CMP circuit short to GND
CMP circuit short to PWR
SIG RTN open (VR sensor)
CMP GND open (Hall effect sensor)
CMP misinstalled (Hall effect sensor)
Damaged CMP sensor shielding
Damaged CMP sensor
Damaged PCM
Harness routing, harness alterations, improper shielding, or electrical interference from other improperly functioning systems may have intermittent impact on the CMP signal.
P0350 - Ignition Coil (Undetermined) Primary/ Secondary Circuit Malfunction Each ignition primary circuit is continuously monitored. The test fails when the PCM does not receive a valid IDM pulse signal from the ignition module (integrated in PCM). Open or short in Ignition START/RUN circuit
Open coil driver circuit
Coil driver circuit shorted to ground
Damaged coil
Damaged PCM
Coil driver circuit shorted to VPWR
P0351 Through P0360 - Ignition Coil A through J Primary/ Secondary Circuit Malfunction Each ignition primary circuit is continuously monitored. The test fails when the PCM does not receive a valid IDM pulse signal from the ignition module (integrated in PCM). Open or short in Ignition START/RUN circuit
Open coil driver circuit in harness
Coil driver circuit shorted to ground
Damaged coil
Damaged PCM
Coil driver circuit shorted to PWR
P0400 EGR Flow Failure (outside the minimum or maximum limits) The EEGR system is monitored once per drive cycle during steady state conditions above 48 mph . The test will fail when a malfunction is detected by PCM calculations indicating the EGR flow is less or greater than expected. EEGR valve stuck open or closed
Connector to EEGR not seated
EEGR motor windings shorted or open circuited
No power to EEGR
Harness open or shorted to power or ground
Vacuum signal to MAP restricted or leaking
MAF sensor signal erroneous
Damaged PCM
Carbon build up in EEGR valve seat area
One or more sensor not responding or out of range
All of the following sensors input data to the PCM for proper operation of the EEGR system: ECT, CPS, IAT, MAF, TP, MAP. Any DTC relating to these sensors must be resolved prior to addressing
P0400 code.
P0401 - EGR Flow Insufficient Detected The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum. Vacuum supply
EGR valve stuck closed
EGR valve leaks vacuum
EGR flow path restricted
EGRVR circuit shorted to PWR
VREF open to D.P.F. EGR sensor
D.P.F. EGR sensor downstream hose off or plugged
EGRVR circuit open to PCM
VPWR open to EGRVR solenoid
D.P.F. EGR sensor hoses both off
D.P.F. EGR sensor hoses reversed
Damaged EGR orifice tube
Damaged EGRVR solenoid
Damaged PCM
Perform KOER self-test and look for DTC P1408 as an indication of a hard fault. If P1408 is not present, look for contamination, restrictions, leaks, and intermittents.
P0402 - EGR Flow Excessive Detected The EGR system is monitored for undesired EGR flow during idle. The EGR monitor looks at the DPF EGR signal at idle and compares it to the stored signal measured during key ON and engine OFF. The test fails when the signal at idle is greater than at key ON engine OFF by a calibrated amount. EGR valve stuck open
Plugged EGR vacuum regulator solenoid vent
Plugged EGR tube
Slow responding D.P.F. EGR sensor
Damaged DPF EGR sensor
Improper vacuum hose connection
Plugged vacuum hoses
EGRVR circuit shorted to ground
Damaged EGR vacuum regulator solenoid
Damaged PCM
A DPFEGR PID reading that is greater at idle than during key ON and engine OFF by 0.5 volt or a rough engine idle, may indicate a hard fault.
P0403 EEGR Electric Motor Windings Or Circuits To The PCM Shorted Or Open The EEGR system is continously monitored to check the 4 EEGR motor coils, circuits, and the PCM for opens, shorts to power and ground. If a malfunction is detected the EEGR system will be disabled and additional monitoring will be suspended for the remainder of the drive until the next drive cycle. EEGR motor windings open
Connector to EEGR not seated
Open circuit in harness from PCM to EEGR
Open circuit in PCM
Short circuit in EEGR motor
Short circuit in harness from PCM to EEGR
Short circuit in PCM
If an intermittent condition is suspected the most effective methoid of wiring fault isolation is to use the wiggle test methoid while measuring for shorts and open circuits.
P0411 - Secondary Air Injection (AIR) system upstream flow See DTC P1411
P0412 - Secondary Air Injection System (AIR) circuit malfunction The PCM attempts to control when air is injected in the exhaust. The DTC indicates a Secondary Air injection system AIR circuit fault. AIR circuit open
AIR bypass solenoid fault
Damaged PCM
AIR circuit short to power
Solid state relay fault
Damaged AIR pump
The AIR circuit is normally held high through the AIR bypass solenoid and SSR when the output driver is off. Therefore, a low AIR circuit indicates a driver is always on and a high circuit indicates an open in the PCM.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1) Indicates Bank 1 catalyst system efficiency is below the acceptable threshold Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler/tailpipe assembly
Retarded spark timing
Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
P0430 - Catalyst System Efficiency Below Threshold (Bank 2) Indicates Bank 2 catalyst system efficiency is below the acceptable threshold. Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler/tailpipe assembly
Retarded spark timing
Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
P0442 - EVAP Control System Leak Detected (Small Leak) The PCM monitors the complete EVAP control system for presence of a small fuel vapor leak. The system failure occurs when a fuel vapor leak from an opening as small as 1.016 mm (0.04 inch) is detected by the EVAP running loss monitor test. After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
Small holes or cuts in fuel vapor hoses/tubes
Canister vent solenoid stays partially open on closed command
Damaged, cross-threaded or loosely installed fuel filler cap
Loose fuel vapor hose/tube connections to EVAP system components
EVAP system component seals leaking (EVAP canister purge valve, fuel tank pressure sensor, canister vent solenoid, fuel vapor control valve tube assembly or fuel vapor vent valve assembly)
P0443 - EVAP Control System Canister Purge Valve Circuit Malfunction The PCM monitors the EVAP canister purge valve circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified purge duty cycle by PCM command. VPWR circuit open
EVAP canister purge valve circuit shorted to GND
Damaged EVAP canister purge valve
EVAP canister purge valve circuit open
EVAP canister purge valve circuit shorted to VPWR
Damaged PCM
Monitor EVAPPDC PID and voltage between EVAP canister valve signal and PWR GND in output test mode with key ON engine OFF (or in key ON engine RUNNING mode). EVAPPDC PID at 0% and voltage less than 1.0 volts (or EVAPPDC PID at 100% and voltage less than 0.5 volts) indicates a hard fault.
P0451 - FTP Sensor Circuit Noisy The fuel tank pressure changes greater than 14 inches of H 2 0 in 0.10 seconds. Intermittent open or short in the FTP sensor or the FTP sensor signal.
Monitor FTP PID and does it change from above 15 inches of H 2 0 to below a minus (-) 15 inches of H 2 0 often in 1.0 minute.
P0452 - FTP Sensor Circuit Low Voltage Detected The PCM monitors the EVAP control system FTP sensor input signal to the PCM. The test fails when the signal average drops below a minimum allowable calibrated parameter. Contamination internal to FTP sensor connector
Damaged PCM
FTP circuit shorted to GND or SIG RTN
Damaged FTP sensor
FTP V PID reading less than 0.22 volt with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0453 - FTP Sensor Circuit High Voltage Detected The PCM monitors the EVAP control system FTP sensor input signal to the PCM. The test fails when the signal average jumps above a minimum allowable calibrated parameter. FTP circuit open
VREF shorted to VPWR
Damaged PCM
FTP circuit shorted to VREF or VPWR
SIG RTN circuit open
Damaged FTP sensor
FTP V PID reading greater than 4.50 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0455 - EVAP Control System Leak Detected (No Purge Flow or Large Leak) The PCM monitors the complete EVAP control system for no purge flow, the presence of a large fuel vapor leak or multiple small fuel vapor leaks. The system failure occurs when no purge flow (attributed to fuel vapor blockages or restrictions), a large fuel vapor leak or multiple fuel vapor leaks are detected by the EVAP running loss monitor test with the engine running (but not at idle). After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube
EVAP canister purge valve stuck closed
Damaged EVAP canister
Damaged or missing fuel filler cap
Insufficient fuel filler cap installation
Loose fuel vapor hose/tube connections to EVAP system components
Blockages or restrictions in fuel vapor hoses/tubes (items also listed under disconnections or cracks)
Fuel vapor control valve tube assembly or fuel vapor vent valve assembly blocked
Canister vent (CV) solenoid stuck open
Mechanically inoperative fuel tank pressure (FTP) sensor
Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank.
P0456 - EVAP Control System Leak Detected (Very Small Leak) The PCM monitors the complete EVAP control system for the presence of a very small fuel vapor leak. The system failure occurs when a fuel vapor leak from an opening as small as 0.508 mm (0.020 inch) is detected by the EVAP running loss monitor test. Very small holes or cuts in fuel vapor hoses/tubes.
Loose fuel vapor hose/tube connections to EVAP system components.
EVAP system component seals leaking (refer to Possible Causes under DTC P0442).
P0457 - EVAP Control System Leak Detected (Fuel Filler Cap Loose/Off) A fuel tank pressure change greater than a minus (-) 7 inches of H 2 0 in 30 seconds has occurred after refueling; or there is excessive purge (fuel vapor) flow greater than 0.06 pounds per minute. Fuel filler cap not installed on refueling (storing continuous memory DTC) and "check Fuel Cap" light may also be illuminated.
Fuel filler cap missing, loose or cross-threaded.
Check for missing fuel filler cap or integrity of the cap. If OK, clear continuous memory DTCs and re-initiate EVAP Emission Running Loss Monitor Drive Cycle.
P0460 - Fuel Level Sensor Circuit Malfunction The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified fuel fill percentage in the fuel tank. Empty fuel tank
Fuel pump (FP) module stuck open
Incorrectly installed fuel gauge
Damaged instrument cluster
CASE GND circuit open
FLI shorted to VPWR
Damaged PCM
Overfilled fuel tank
Fuel pump (FP) module stuck closed
Damaged fuel gauge
FLI circuit open
FLI circuit shorted to CASE GND or PWR GND
CSE GND shorted to VPWR
Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.
P0500 - Vehicle Speed Sensor (VSS) Malfunction Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS), anti-lock brake system (ABS) control module, generic electronic module (GEM), or central timer module (CTM). If the engine rpm is above the torque converter stall speed (automatic transmission) and engine load is high, it can be inferred that the vehicle must be moving. If there is insufficient vehicle speed data input, a malfunction is indicated and a DTC is set. On most vehicle applications the malfunction indicator lamp (MIL) will be triggered when this DTC is set. Open in VSS+/VSS- harness circuit.
Open in TCSS signal or TCSS signal return harness circuit.
Short to GND in VSS harness circuit.
Short to GND in TCSS harness circuit.
Short to PWR in VSS harness circuit.
Short to PWR in TCSS harness circuit.
Open or short in the vehicle speed circuit(s) (VSC) between the PCM and appropriate control module.
Damaged VSS or TCSS.
Damaged wheel speed sensors.
Damaged wheel speed sensor harness circuits.
Damage in module(s) connected to VSC/VSS circuit.
Damage drive mechanism for VSS or TCSS.
Monitor VSS PID while driving vehicle. This DTC is set when the PCM detects a sudden loss of vehicle speed signal over a period of time. If vehicle speed data is lost, check the source of where the vehicle speed input originates from: VSS, TCSS, ABS, GEM or CTM. Note: On some MSOF applications, VSS and TCSS PID can be monitor. However if no TCSS PID is available and VSS PID is zero, TCSS circuitry frequency must be checked for loss of sensor signal. If another vehicle electronic module has generated the P0500 and the vehicle does not receive its vehicle speed input from one of the above mention sources (VSS, TCSS, ABS, GEM or CTM). Check the PCM for Output Shaft Speed Sensor (OSS) DTCs. On OSS applications the PCM uses the OSS to calculated the vehicle speed. If no OSS DTCs are found check for correct PCM configuration. Check PCM configuration for correct tire size and axle ratio.
P0501 - Vehicle Speed Sensor (VSS) Range/ Performance Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. This DTC is set the same way as P0500, however the malfunction indicator lamp (MIL) is not triggered. Refer to possible causes for P0500.
Refer to diagnostic aids for P0500.
P0503 - Vehicle Speed Sensor (VSS) Intermittent Indicates poor or noisy VSS performance. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS), anti-lock brake system (ABS) control module, generic electronic module (GEM), or central timer module (CTM). Noisy VSS/TCSS input signal from Radio Frequency Interference/ Electro-Magnetic Interference (RFI/EMI) external sources such as ignition components or charging circuit.
Damaged VSS or driven gears.
Damaged TCSS.
Damaged wiring harness or connectors.
Malfunction in module(s) or circuit connected to VSS/TCSS circuit.
After market add-on.
Monitor VSS PID while driving vehicle, check for intermittent vehicle speed indication. Verify ignition and charging system are functioning correctly.
P0505 - Idle Air Control System Malfunction The PCM attempts to control engine speed during KOER self-test. The test fails when the desired rpm could not be reached or controlled during the self-test. IAC circuit open
VPWR to IAC solenoid open
IAC circuit shorted to PWR
Air inlet is plugged
Damaged IAC valve
Damaged PCM
The IAC solenoid resistance is from 6 to 13 ohms.
P0552 - Power Steering Pressure (PSP) Sensor Circuit Malfunction The PSP sensor input signal to the PCM is continuously monitored.The test fails when the signal is open or shorted to ground. PSP sensor damaged
SIG RTN circuit open or shorted
VREF circuit open or shorted
PSP sensor signal circuit open or shorted
Damaged PCM
The DTC indicates the PSP sensor circuit is open or shorted to ground.
P0553 - Power Steering Pressure (PSP) Sensor Circuit Malfunction The PSP sensor input signal to PCM is continuously monitored. The test fails when the signal is shorted to power. PSP sensor damaged
SIG RTN circuit shorted to power
VREF circuit shorted to power
PSP sensor signal circuit shorted to power
Damaged PCM
The code indicates the PSP sensor circuit is shorted to power.
P0602 - Control Module Programming Error This Diagnostic Trouble Code (DTC) indicates programming error within Vehicle ID block (VID). VID data corrupted by the scan tool during VID reprogramming
Using the scan tool, reprogram the VID block. If PCM does not allow reprogramming of the VID block, reflashing PCM will be required.
P0603 - Powertrain Control Module KAM Test Error Indicates the PCM has experienced an internal memory fault. However there are external items that can cause this DTC. Reprogramming
Battery terminal corrosion
KAPWR to PCM interrupt/open
Loose battery connection
Damaged PCM
If KAPWR is interrupted to the PCM because of a battery or PCM disconnect, DTC can be generated on the first power-up.
P0605 - PCM read only memory (ROM) error Indicates the PCM ROM has been corupted. An attempt was made to change the calibration.
Module programming error.
Damaged PCM
Reprogram or update calibration.
Reprogram VID block (use as built data).
Check for other DTC's or drive symptoms for further action.
P0703 - Brake Switch Circuit Input Malfunction Indicates PCM did not receive a brake pedal position (BPP) input. Open or short in BPP circuit
Open or short in stoplamp circuits
Damaged PCM
Malfunction in module(s) connected to BPP circuit. (Rear Electronic Module [REM] Windstar and LS6/LS8 or Lighting Control Module (LCM) Continental and Town Car.
Damaged brake switch
Misadjusted brake switch
Check for proper function of stoplamps. Follow correct Self-Test procedures, refer to Section 2 of Quick Test.
P0704 - Clutch Pedal Position Switch Malfunction When the clutch pedal is depressed the voltage goes to low. If the PCM does not see this change from high to low the DTC is set. CPP circuit short to PWR
Damaged CPP switch
CPP circuit open in the SIGRTN
Damaged PCM
When depressing the CPP switch the voltage should cycle from 5.0V down.
P0720 - Insufficient input from Output Shaft Speed sensor The output shaft speed sensor inputs a signal to the PCM, based on the speed of the output shaft of the transmission. The PCM compares this signal with the signal of the VSS or TCSS and determines correct tire size and axle gear ratio. OSS sensor circuit short to GND
OSS sensor circuit short to PWR
OSS sensor circuit open
Damaged OSS sensor
Damaged PCM
Verify sensor signal output varies with vehicle speed.
P0721 - Noise interference on Output Shaft Speed sensor signal The output shaft speed sensor signal is very sensitive to noise. This noise distorts the input to the PCM. Wiring misrouted
After market add-on
Wiring damaged
Wiring insulation wear
Check routing of harness.
Check wiring and connector for damage.
P0722 - No signal from Output Shaft Speed sensor The output shaft speed sensor failed to provide a signal to the PCM upon initial movement of vehicle. Damaged OSS connector
Damaged OSS sensor, or not installed properly
Harness intermittently shorted or open
P0723 - Output Shaft Speed sensor circuit intermittent failure The output shaft speed sensor signal to the PCM is irregular or interrupted. Harness connector not properly seated
Harness intermittently shorted, or open
Harness connector damaged
OSS sensor damaged, or not installed properly
Verify harness and connector integrity
Verify OSS sensor proper installation
P0812 - Reverse Switch (RS) input circuit malfunction The DTC indicates that the voltage is high when it should be low. Transmission shift not indicating neutral while in KOEO Self-Test
RS circuit short to PWR
Damaged reverse switch
RS circuit open or short to SIGRTN
Damaged PCM
Check RS PID while exercising shift lever in and out of reverse.
P1000 - Monitor Testing Not Complete The on board diagnostic II (OBD II) monitors are performed during the OBD II Drive Cycle. The DTC will be stored in continuous memory if any of the OBD II monitors do not complete. Vehicle is new from the factory
Battery or PCM had recently been disconnected
An OBD II monitor failure had occurred before completion of an OBD II drive cycle
PCM DTCs have recently been cleared with a scan tool
PTO circuit is shorted to VPWR or B+ or PTO is on during testing
The DTC does not need to be cleared from the PCM except to pass an inspection/maintenance test.
P1001 - KOER Not Able To Complete, KOER Aborted This Non-MIL (Malfunction Indicator Lamp) code will be set when Key On Engine Running (KOER) Self-Test does not complete in the time intended. Incorrect Self-Test Procedure.
Unexpected response from Self-Test monitors.
rpm out of specification.
Rerun Self-Test following QT1 in Section 3 , Symptom Charts, STEP 1: PCM Quick Test.
P1100 - Mass Air Flow (MAF) Sensor Intermittent The MAF sensor circuit is monitored by the PCM for sudden voltage (or air flow) input change through the comprehensive component monitor (CCM). If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory diagnostic trouble code (DTC) is stored. Poor continuity through the MAF sensor connectors
Poor continuity through the MAF sensor harness
Intermittent open or short inside the MAF sensor.
While accessing the MAF V PID on the scan tool, lightly tap on the MAF sensor or wiggle the MAF sensor connector and harness. If the MAF V PID suddenly changes below 0.23 volt or above 4.60 volts, an intermittent fault is indicated.
P1101 - Mass Air Flow (MAF) Sensor Out of Self-Test Range The MAF sensor circuit is monitored by the PCM for an out of range air flow (or voltage) input. If during key ON engine OFF the air flow voltage signal is greater than 0.27 volts the test fails. Likewise, if during key ON engine running, an air flow voltage signal is not within 0.46 volt to 2.44 volts, the test fails. For voltage to air flow gm/sec conversion, GO to Pinpoint Test DC and refer to Voltage To Mass Air Flow Conversion Table. Low battery charge
MAF sensor partially connected
MAF sensor contamination
PWR GND open to MAF sensor
MAF RTN circuit open to PCM
Damaged MAF sensor
Damaged PCM
A MAF V PID reading greater than 0.27 volts (KOEO) or a MAF V PID reading outside the 0.46 volt to 2.44 volts range (KOER) indicates a hard fault.
P1112 - Intake Air Temperature (IAT) Sensor Intermittent Indicates IAT sensor signal was intermittent during the comprehensive component monitor. Damaged harness
Damaged sensor
Damaged harness connector
Damaged PCM
Monitor IAT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.
P1114 - Intake Air Temperature 2 Circuit Low Input Indicates the sensor signal is less than Self-Test minimum. The IAT2 sensor minimum is 0.2 volts. Grounded circuit in harness
Improper harness connection
Damaged sensor
Damaged PCM
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P1115 - Intake Air Temperature 2 Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The IAT2 sensor maximum is 4.6 volts. Open circuit in harness
Sensor signal short to power
Improper harness connection
Damaged sensor
Damaged PCM
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P1116 - Engine Coolant Temperature (ECT) Sensor Out of Self-Test Range Indicates the ECT sensor is out of Self-Test range. Correct range is 0.3 to 3.7 volts. Overheating condition
Malfunctioning thermostat
Damaged ECT sensor
Low engine coolant
Damaged harness connector
Damaged PCM
Engine coolant temperature must be greater than 10°C (50°F) to pass the KOEO Self-Test and greater than 82°C (180°F) to pass the KOER Self-Test.
P1117 - Engine Coolant Temperature (ECT) Sensor Intermittent Indicates ECT circuit became intermittently open or shorted while engine was running. Damaged harness
Damaged sensor
Damaged PCM
Damaged harness connector
Low engine coolant
Monitor ECT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.
P1120 - Throttle Position (TP) Sensor Out of Range Low (RATCH too Low) The TP sensor circuit is monitored by the PCM for a low TP rotation angle (or voltage) input below the closed throttle position through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) remains within the calibrated self-test range but falls between 3.42 and 9.85% (0.17 and 0.49 volt), the test fails. TP circuit with frayed wires
Corrosion on TP circuit connectors
VREF open to TP sensor
VREF short to SIG RTN
TP sensor loose pins
A TP PID (TP V PID) between 3.42 and 9.85% (0.17 and 0.49 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.
P1121 - Throttle Position (TP) Sensor Inconsistent with MAF Sensor The PCM monitors a vehicle operation rationality check by comparing sensed throttle position to mass air flow readings. If during key ON engine running self-test the comparison of the TP sensor and MAF sensor readings are not consistent with calibrated load values, the test fails and a diagnostic trouble code is stored in continuous memory. Air leak between MAF sensor and throttle body
TP sensor not seated properly
Damaged TP sensor
Damaged MAF sensor
Drive vehicle and exercise throttle and TP sensor in all gears. A TP PID (TP V PID) less than 4.82 % (0.24 volt) with a LOAD PID greater than 55% or a TP V PID greater than 49.05% (2.44 volts) with a LOAD PID less than 30% indicates a hard fault.
P1124 - Throttle Position (TP) Sensor Out of Self-Test Range The TP sensor circuit is monitored by the PCM for an out of range TP rotation angle (or voltage) input. If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) reading is less than 13.27% (0.66 volt) or greater than 23.52% (1.17 volts), the test fails. Binding or bent throttle linkage
TP sensor not seated properly
Throttle plate below closed throttle position
Throttle plate/screw misadjusted
Damaged TP sensor
Damaged PCM
A TP PID (TP V PID) reading not between 13.27 and 23.52% (0.66 and 1.17 volts) in key ON engine OFF or key ON engine running indicates a hard fault.
P1125 - Throttle Position (TP) Sensor Intermittent The TP sensor circuit is monitored by the PCM for sudden TP rotation angle (or voltage) input change through the comprehensive component monitor (CCM). If during the last 80 warm-up cycles in key ON engine running the PCM detects a TP rotation angle (or voltage) changes beyond the minimum or maximum calibrated limit, a continuous diagnostic trouble code (DTC) is stored. Poor continuity through the TP sensor connectors
Poor continuity through the TP harness
Intermittent open or short inside the TP sensor
While accessing the TP V PID on the scan tool, lightly tap on the TP sensor or wiggle the TP sensor connector and harness. If the TP V PID suddenly changes below 0.49 volt or above 4.65 volts, an intermittent fault is indicated.
P1127 - Exhaust Not Warm Enough, Downstream Sensor Not Tested The HEGO monitor uses an exhaust temperature model to determine when the HO2S heaters are cycled ON. The test fails when the inferred exhaust temperature is below a minimum calibrated value. Engine not operating long enough prior to performing KOER self-test.
Exhaust system too cool.
Monitor HO2S Heater PIDs to determine their ON/OFF state. DTC P1127 will be present if the exhaust is not hot.
P1128 - Upstream Oxygen Sensors Swapped from Bank to Bank (HO2S-11-21) The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated. Crossed HO2S harness connectors (upstream).
Crossed HO2S wiring at the harness connectors (upstream).
Crossed HO2S wiring at the 104-pin harness connectors (upstream).
P1129 - Downstream Oxygen Sensors Swapped from Bank to Bank (HO2S-12-22) The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated. Crossed HO2S harness connectors (downstream).
Crossed HO2S wiring at the harness connectors (downstream).
Crossed HO2S wiring at the 104-pin harness connectors (downstream).
P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit. Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)
A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.
P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1132 - Lack of HO2S-11 Switch, Sensor Indicates Rich A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1137 - Lack of HO2S-12 Switch, Sensor Indicates Lean The downstream HO2S sensors are forced rich and lean and monitored by the PCM. The test fails if the PCM does not detect the output of the HO2S in a calibrated amount of time. Pinched, shorted, and corroded wiring and pins
Crossed sensor wires
Exhaust leaks
Contaminated or damaged sensor
P1138 - Lack of HO2S-12 Switch, Sensor Indicates Rich See DTC P1137
P1150 - Lack of HO2S-21 Switch, Fuel Trim at Limit See DTC P1130
P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1152 - Lack of HO2S-21 Switch, Sensor Indicates Rich A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1157 - Lack of HO2S-22 Switch, Sensor Indicates Lean See DTC P1137
P1158 - Lack of HO2S-22 Switch, Sensor Indicates Rich See DTC P1137
P1168 - Fuel Rail Pressure Sensor in Range But Low The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below a calibrated value. Low fuel pressure
Damaged FRP sensor
Excessive resistance in circuit
Low or no fuel
A FRP PID value below 551 kpa (80 psi) indicates a failure
Low or no fuel
A FRP PID value greater than 896 kpa (130 psi) indicates a failure
DTC - Description Possible Causes Diagnostic Aides
P0102 - Mass Air Flow (MAF) Circuit Low Input
The MAF sensor circuit is monitored by the PCM for low air flow (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine running the air flow (or voltage) changes below a minimum calibrated limit, the test fails. MAF sensor disconnected
MAF circuit open to PCM
VPWR open to MAF sensor
PWR GND open to MAF sensor
MAF RTN circuit open to PCM
MAF circuit shorted to GND
Intake air leak (near MAF sensor)
A closed throttle indication [throttle position (TP) sensor system]
Damaged MAF sensor
Damaged PCM
A MAF V PID (MAF PID) reading less than 0.23 volts (Refer to equivalent grams/second chart in GO to Pinpoint Test DC ) in continuous memory or key ON and engine running indicates a hard fault.
P0103 - Mass Air Flow (MAF) Circuit High Input The MAF sensor circuit is monitored by the PCM for high air flow (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the air flow (or voltage) changes above a maximum calibrated limit, the test fails. MAF sensor screen is blocked
MAF circuit shorted to VPWR
Damaged MAF sensor
Damaged PCM
A MAF V PID (MAF PID) reading less than 4.6 volts (Refer to equivalent grams/second chart in GO to Pinpoint Test DC ) in continuous memory or key ON and engine running indicates a hard fault.
P0106 - Barometric (BARO) Pressure Sensor Circuit Performance Baro sensor input to the PCM is monitored and is not within the calibrated value. Slow responding BARO sensor
Electrical circuit failure
Damaged BARO sensor
Damaged PCM
VREF voltage should be between 4.0 and 6.0 volts
PID reading is in frequency
P0107 - BARO/MAP Sensor Low Voltage Detected Sensor operating voltage is less than 0.25 volts (VREF), as a result it failed below the minimum allowable calibrated parameter. Open in the circuit, or short to ground
VREF circuit open, or short to ground
Damaged BARO/MAP sensor
Damaged PCM
VREF should be greater than 4.0 volts
PID reading is in frequency/volts
P0108 - BARO/MAP Sensor High Voltage Detected Sensor operating voltage is greater than 5.0 volts (VREF), as a result it failed above maximum allowable calibrated parameter. VREF shorted to VWPR
BARO/MAP signal shorted to VPWR
Damaged BARO/MAP sensor
Damaged PCM
VREF should be less than 6.0 volts. PID reading is in frequency/Volts
P0109 - BARO/MAP Sensor Circuit Intermittent The sensor signal to the PCM is failing intermittently. Loose electrical connection
Damaged BARO/MAP sensor
Check harness and connection.
P0112 - Intake Air Temperature (IAT) Circuit Low Input Indicates the sensor signal is less than Self-Test minimum. The IAT sensor minimum is 0.2 volts or 121°C (250°F). Grounded circuit in harness
Damaged sensor
Improper harness connection
Damaged PCM
IAT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0113 - Intake Air Temperature (IAT) Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The IAT sensor maximum is 4.6 volts or -50°C (-58°F). Open circuit in harness
Sensor signal short to power
Damaged sensor
Improper harness connection
Damaged PCM
IAT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0116 - Engine Coolant Temperature Circuit Range/Performance Failure Indicates the engine coolant temperature rationality test has failed. The PCM logic that sets this DTC indicates that engine coolant temperature sensor (ECT or CHT) drifted higher than the nominal sensor calibration curve and could prevent one or more OBD II monitors from executing.
The PCM runs this logic after an engine off "calibrated soak period (typically 6 hours). This soak period allows the Intake Air Temperature (IAT) and engine coolant temperature (CHTor ECT) to stabilize and not differ by more than a calibrated value. DTC P0116 is set when all of the following conditions are met:
Engine coolant temperature at engine start exceeds IAT at engine start by more than a calibrated value, typically 30°F (1°C).
Engine coolant temperature exceeds a calibrated value, typically 225F (107C).
The Fuel, Heated Oxygen Sensor, Catalyst and Misfire monitors have not completed.
Calibrated timer to set DTC P0116 has expired.
Engine Coolant Temperature (ECT) or Cylinder Head Temperature (CHT) sensor
Coolant System Concern
Ensure IAT and engine coolant temperature are similar when engine is cold. Also ensure engine coolant temperature sensor (ECT or CHT) and actual engine operating temperature are the same.
P0117 - Engine Coolant Temperature (ECT) Circuit Low Input Indicates the sensor signal is less than Self-Test minimum. The ECT sensor minimum is 0.2 volts or 121°C (250°F). Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC. Grounded circuit in harness
Damaged sensor
Improper harness connection
Damaged PCM
ECT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0118 - Engine Coolant Temperature (ECT) Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The ECT sensor maximum is 4.6 volts or -50°C (-58°F). Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC. Open circuit in harness
Sensor signal short to power
Damaged PCM
Improper harness connection
Damaged sensor
ECT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0121 - Throttle Position (TP) Circuit Performance Problem The TP sensor circuit is monitored by the PCM for a non closed throttle position at idle. If key ON engine running self-test terminates upon placing the transmission range selector in gear (DRIVE or REVERSE) or when closing the throttle (idle) after opening it (in PARK or NEUTRAL) the TP closed throttle position is not attained, the test fails. Binding throttle linkage
Damaged throttle body
TP circuit open to PCM
Damaged TP sensor
SIG RTN circuit open to TP sensor
Drive vehicle, bring to a stop, turn key OFF. Start vehicle, run key ON engine running self-test at idle. Access KOER diagnostic trouble codes on scan tool.
P0122 - Throttle Position (TP) Circuit Low Input The TP sensor circuit is monitored by the PCM for a low TP rotation angle (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) changes below a minimum calibrated limit, the test fails. TP sensor not seated properly
TP circuit open to PCM
VREF open to TP sensor
TP circuit short to GND
Damaged TP sensor
Damaged PCM
A TP PID (TP V PID) reading less than 3.42% (0.17 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.
P0123 - Throttle Position (TP) Circuit High Input The TP sensor circuit is monitored by the PCM for a high TP rotation angle (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) changes above maximum calibrated limit, the test fails. TP sensor not seated properly
TP circuit short to PWR
VREF short to PWR
SIG RTN circuit open to TP sensor
Damaged TP sensor
Damaged PCM
A TP PID (TP V PID) reading greater than 93% (4.65 volts) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.
P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control Indicates the ECT or CHT sensor has not achieved the required temperature level to enter closed loop operating conditions within a specified amount of time after starting engine. Insufficient warm up time
Low engine coolant level
Leaking or stuck open thermostat
Malfunctioning ECT sensor
Malfunctioning CHT sensor
Refer to Thermostat Monitor in Section 1, Description and Operation, for system information.
P0127 - Intake Air Temperature Too High Indicates that IAT2 sensor has detected a potential abnormality in the intercooler system. This condition will cause the boost from the supercharger to be bypassed to avoid potential engine damage. Blockage of heat exchangers
Low fluid level
Fluid leakage
Intercooler pump or relay failure
Crossed intercooler coolant lines
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P0131 - HO2S Sensor Circuit Out of Range Low Voltage (HO2S-11) The HO2S sensor is monitored for a negative voltage known as characteristic shift downward (CSD). If the sensor is thought to be switching from 0 volts to -1 volts during testing, the PCM will use this input and remain in fuel control. Contaminated HO2S (water, fuel, etc)
Crossed HO2S signal/signal return wiring
P0133 - HO2S Sensor Circuit Slow Response (HO2S-11) The HEGO Monitor checks the HO2S Sensor frequency and amplitude. If during testing the frequency and amplitude were to fall below a calibrated limit, the test will fail. Contaminated HO2S sensor.
Exhaust leaks.
Shorted /open wiring.
Improper fueling.
MAF sensor.
Deteriorating HO2S sensor.
Inlet air leaks.
Access HO2S test results from the Generic OBD-II menu to verify DTC.
P0135 - HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S.
Water in harness connector.
Open VPWR circuit.
Open GND circuit.
Low battery voltage.
Corrosion or poor mating terminals and wiring
Damaged HO2S heater.
Damaged PCM.
Wiring.
Damaged HO2S heater.
Damaged PCM.
P0136 - HO2S Sensor Circuit Malfunction (HO2S-12) The downstream HO2S sensor(s) are continuously checked for maximum and minimum voltages. The test fails when the voltages fail to meet the calibrated limits. Pinched, shorted, and corroded wiring and pins.
Crossed sensor wires.
Exhaust leaks.
Contaminated or damaged sensor.
P0141 - HO2S Sensor Circuit Malfunction (HO2S-125) See DTC P0135
P0148 - Fuel Delivery Error At least one bank lean at wide open throttle. Severely restricted fuel filter.
Severely restricted fuel supply line.
P0151 - HO2S Sensor Circuit Out of Range Low Voltage (HO2S-21) See DTC P0131
P0153 - HO2S Sensor Circuit Slow Response (HO2S-21) See DTC P0133
P0155 - HO2S Sensor Circuit Malfunction (HO2S-21) See DTC P0135
P0156 - HO2S Sensor Circuit Malfunction (HO2S-22) See DTC P0136
P0161 - HO2S Sensor Circuit Malfunction (HO2S-22) See DTC P0135
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:
Fuel system
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Induction system:
Air leaks after the MAF.
Vacuum Leaks.
PCV system.
Improperly seated engine oil dipstick.
EGR system:
Leaking gasket.
Stuck EGR valve.
Leaking diaphragm or EVR.
Base Engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
A SHRTFT-1,2 PID value between -25% to +35% and a LONGFT-1,2 PID value between -35% to +35% is acceptable. Reading beyond these values indicate a failure.
P0172 - System to Rich (Bank 1) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit. See Possible Causes for DTC P0171 See Diagnostic Aides for DTC P0171
P0174 - System to Lean (Bank 2) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. See Possible Causes for DTC P0171. See Diagnostic Aides for DTC P0171
P0175 - System to Rich (Bank 2) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit. See Possible Causes for DTC P0171. See Diagnostic Aides for DTC P0171
P0176 - Flexible Fuel (FF) Sensor Circuit Malfunction The FF sensor input signal to PCM is continuously monitored. The test fails when the signal falls out of a maximum or minimum calibrated range. Open or short in FF sensor VPWR circuit
Open in battery ground to FF sensor circuit
Open in FF sensor signal circuit
Short to ground in FF sensor signal circuit
Fuel contamination
Short to VPWR in FF sensor battery ground circuit
Short to VPWR in FF sensor signal circuit
Fuel separation
Damaged FF sensor
Damaged PCM
A flex fuel (FF) PID reading of 0 Hz with the key ON and engine OFF or with engine at idle indicates a hard fault.
P0180 - Engine Fuel Temperature Sensor A Circuit Low Input (EFT) The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for low and high voltage. If voltage were to fall below or exceed a calibrated limit and amount of time during testing, the test will fail. Open or short in harness.
Low ambient temperature operation.
Improper harness connection.
Damaged EFT sensor.
Damaged PCM.
Verify EFT-PID value to determine open or short.
P0181 - Engine Fuel Temperature Sensor A Circuit Range/ Performance (EFT) The comprehensive component monitor (CCM) monitors the EFT Temperature for acceptable operating temperature. If during testing voltage were to fall below or exceed a calibrated limit, a calibrated amount of time the test will fail. Open or short in harness.
Low ambient temperature operation.
Improper harness connection.
Damaged EFT sensor.
Damaged PCM.
Verify EFT-PID value to determine open or short.
P0182 - Engine Fuel Temperature Sensor A Circuit Low Input (EFT) The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for low voltage. If voltage were to fall below a calibrated limit and amount of time during testing, the test will fail. Short in harness.
VREF open or shorted.
Low ambient temperature operation.
Improper harness connection.
Damaged EFT sensor.
Damaged PCM.
Verify EFT-PID and VREF values to determine open or short.
P0183 - Engine Fuel Temperature Sensor A Circuit High Input (EFT) The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for high voltage. If voltage were to exceed a calibrated limit and a calibrated amount of time during testing, the test will fail. Open or short to PWR in harness.
Damaged EFT sensor.
Improper harness connection.
Damaged PCM.
Verify EFT-PID value to determine open or short.
P0186 - Engine Fuel Temperature Sensor B Circuit Range/Performance (EFT) See DTC P0181.
P0187 - Engine Fuel Temperature Sensor B Circuit Low Input (EFT). See DTC P0182.
P0188 - Engine Fuel Temperature Sensor B Circuit High Input (EFT) See DTC P0183.
P0190 - Fuel Rail Pressure Sensor Circuit Malfunction (FRP) The comprehensive component monitor (CCM) monitors the FRP sensor to the PCM for VREF voltage. The test fails when the VREF voltage from the PCM drops to a voltage less than a minimum calibrated value. VREF open in harness.
VREF open in sensor.
VREF open in PCM.
Verify VREF voltage between 4.0 and 6.0V.
P0191 - Fuel Rail Pressure Sensor Circuit Performance (FRP) The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below or exceeds a minimum/maximum calibrated value for a calibrated period of time. High fuel pressure.
Low fuel pressure.
Damaged FRP sensor.
Excessive resistance in circuit.
Low or no fuel.
A FRP PID value during KOER of 138 kpa (20 psi) and 413 kpa (60 psi) for gasoline or 586 kpa (85 psi) and 725 kpa (105 psi) for natural gas vehicles (NG) is acceptable.
P0192 - Fuel Rail Pressure Sensor Circuit Low Input (FRP) The comprehensive component monitor (CCM) monitors the FRP sensor circuit to the PCM for low voltage. If voltage were to fall below a calibrated limit and amount of time during testing, the test will fail. FRP signal shorted to SIG RTN or PWR GND.
FRP signal open (NG only)
Low fuel pressure (NG only)
Damaged FRP sensor.
Damaged PCM.
A FRP PID value during KOER or KOEO less than 0.3 volts for gasoline or 0.5 volts for natural gas vehicles (NG) would indicate a hard fault.
P0193 - Fuel Rail Pressure Sensor Circuit High Input (FRP) The comprehensive component monitor (CCM) monitors the FRP sensor circuit to the PCM for high voltage. If voltage were to fall below a calibrated limit and a calibrated amount of time during testing, the test will fail. FRP signal shorted to VREF or VPWR.
FRP signal open (gasoline only)
Low fuel pressure (NG only)
Damaged FRP sensor.
Damaged PCM.
High fuel pressure (caused by damaged fuel pressure regulator) NG.
A FRP PID value during KOER or KOEO less than 0.3 volts for gasoline or 0.5 volts for natural gas vehicles (NG) would indicate a hard fault.
P0201 through P0212 - Cylinder #1 through Cylinder #12 Injector Circuits The comprehensive component monitor (CCM) monitors the operation of the fuel injector drivers in the PCM. The test fails when the fuel injector does not operate electrically even though the harness assembly and fuel injectors test satisfactorily. Faulty fuel injector driver within the PCM.
PID Data Monitor INJ1F-INJ12F fault flags = YES.
P0217 - Engine Coolant Over-Temperature Condition Indicates an engine overheat condition was detected by the cylinder head temperature (CHT) sensor. This condition will cause the boost from the supercharger to be bypassed to avoid potential engine damage. Engine cooling system concerns.
Low engine coolant level.
Base engine concerns.
Monitor CHT PID for overheat condition. Typical CHT temperature should be close to cooling system thermostat opening specification.
P0230 - Fuel Pump Primary Circuit Malfunction NOTE: For natural gas applications, the following description applies to the fuel shutoff valve (FSV) circuit.
The PCM monitors the fuel pump (FP) circuit output from the PCM. The test fails if: With the FP output commanded ON (grounded), excessive current draw is detected on the FP circuit; or with the FP output commanded OFF, voltage is not detected on the FP circuit (the PCM expects to detect VPWR voltage coming through the fuel pump relay coil to the FP circuit). Open or shorted fuel pump (FP) circuit
Open VPWR circuit to fuel pump relay
Damaged fuel pump relay
Damaged PCM
When the FPF PID reads YES, a fault is currently present.
An open circuit or short to ground can only be detected with the fuel pump commanded OFF.
A short to power can only be detected with the fuel pump commanded ON.
During KOEO and KOER self-test, the fuel pump output command will be cycled ON and OFF.
P0231 - Fuel Pump Secondary Circuit Low NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits.
The PCM monitors the fuel pump monitor (FPM) circuit. The test fails if the PCM commands the fuel pump ON and B+ voltage is not detected on the FPM circuit. Open B+ circuit to the fuel pump relay
Open FP PWR circuit between the fuel pump relay and its connection to the FPM circuit
Damaged fuel pump relay
Damaged PCM (engine will start)
For 4.6L Mustang, open FP PWR circuit from low speed fuel pump relay, through resistor to FPM splice (engine will start)
For 5.4L SC Lightning, damaged IFS switch, IFS switch relay, or concern with related circuits.
During KOEO self-test, the PCM will command the fuel pump ON so this test can be performed.
P0232 - Fuel Pump Secondary Circuit High NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits.
The PCM monitors the fuel pump monitor (FPM) circuit. This test fails when the PCM detects voltage on the FPM circuit while the fuel pump is commanded OFF. The FPM circuit is wired to a pull-up voltage inside the PCM. The FPM circuit will go high if, with the key ON and the fuel pump commanded OFF, the FPM/FP PWR circuit loses its path to ground through the fuel pump. The FPM circuit will also go high if the FPM/FP PWR circuit is shorted to power.
Inertia fuel shutoff (IFS) switch not reset or electrically open
Open circuit between the fuel pump and the FPM connection to the FP PWR circuit
Poor fuel pump ground
Fuel pump electrically open
Fuel pump secondary circuits short to power
Fuel pump relay contacts always closed
Open FPM circuit between PCM and connection to FP PWR circuit
Damaged low speed fuel pump relay or concern with related circuits (if equipped).
Damaged PCM
Continuous memory P0232 can be set if the IFS switch was tripped, then reset, or if the fuel pump circuit is activated when the PCM expected the circuit to be off (i.e. fuel system test or prime procedure).
P0234 - Supercharger Overboost Condition The PCM disables (bypasses) the supercharger boost and sets a diagnostic trouble code (DTC) to keep from damaging the powertrain (engine or transmission) during potential harmful operating conditions. Brake torque (brake on and throttle at wide open)
Transmission oil temperature (TOT) exceeds calibrated threshold
Engine over temperature
Ignition misfire exceeds calibrated threshold
Knock sensor (KS) failure or knock detected
Low speed fuel pump relay not switching
Check for other diagnostic trouble codes accompanying the P0234 or check appropriate and available PIDs related to above possible causes.
P0243 - Supercharger (Boost) Bypass Solenoid Circuit Malfunction The PCM monitors the supercharger (boost) bypass (SCB) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified SCB solenoid duty cycle (100% or 0%) by PCM command. VPWR circuit open to SCB solenoid
SCB solenoid circuit shorted to PWR GND or CHASSIS GND
Damaged SCB solenoid
SCB solenoid circuit open
SCB solenoid circuit shorted to VPWR
Damaged PCM
Disconnect SCB solenoid. Connect test lamp to SCB solenoid harness connector. Cycle SCB driver in PCM by Output Test Mode. Test lamp cycle on and off - SCB solenoid is suspect. Test lamp always on - SCB signal short in harness or PCM. Test always off - SCB signal or VPWR open in harness or PCM.
P0298 - Engine Oil Over Temperature Condition Indicates the Engine Oil Temperature Protection strategy in the PCM has been activated. This will temporarily prohibit high engine speed operation by disabling injectors, therefore reducing the risk of engine damage from high engine oil temperature. Note: On engines which are equipped with an oil temperature sensor, the PCM reads oil temperature to determine if it is excessive. When an oil temperature sensor is not present, the PCM uses an oil algorithm to infer actual temperature. Engine shutdown strategy function is the same on vehicles with and without oil temperature sensors. Very high engine rpm for extended period of time.
Over-heating condition.
Malfunction EOT sensor or circuit (vehicles w/EOT sensor).
Base engine concerns.
Engine operating in high rpm range, due to improper gear selection. May cause Lack/Loss of Power or Surge customer concern.
P0300 - Random Misfire The random misfire DTC indicates multiple cylinders are misfiring or the PCM cannot identify which cylinder is misfiring. Camshaft position sensor (CMP)
Low fuel: less than 1/8 tank
Stuck open EGR valve
Blocked EGR passages
One or more EGR passages may be blocked or partially blocked. If this is the case the Misfire Detection Monitor will indicate the EGR port to check for possible blockage.
P0301 through P0310 - Misfire Detection Monitor The misfire detection monitor is designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. Ignition system
Fuel injectors
Running out of fuel
EVAP canister purge valve
Fuel pressure
Evaporative emission system
Base engine
The MIL will blink once per second when a misfire is detected severe enough to cause catalyst damage. If the MIL is on steady state, due to a misfire, this will indicate the threshold for emissions was exceeded and cause the vehicle to fail an inspection and maintenance tailpipe test.
P0320 - Ignition Engine Speed Input Circuit Malfunction The ignition engine speed sensor input signal to PCM is continuously monitored. The test fails when the signal indicates that two successive erratic profile ignition pickup (PIP) pulses have occurred. Loose wires/connectors.
Arcing secondary ignition components (coil, wires and plugs)
On board transmitter (2-way radio)
The DTC indicates that two successive erratic PIP pulses occurred.
P0325 - Knock Sensor 1 Circuit Malfunction (Bank 1) See DTC P0326
P0326 - Knock Sensor 1 Circuit Range/ Performance (Bank 1) The knock sensor detects vibrations upon increase and decrease in engine rpm. The knock sensor generates a voltage based on this vibration. Should this voltage go outside a calibrated level a DTC will set. Knock sensor circuit short to GND
Knock sensor circuit short to PWR
Knock sensor circuit open
Damaged knock sensor
Damaged PCM
A knock sensor voltage greater than 0.5V with the key ON and engine OFF indicates a hard fault.
P0330 - Knock Sensor 2 Circuit Malfunction (Bank 2) See DTC P0331
P0331 - Knock Sensor 2 Circuit Range/performance (Bank 2) The knock sensor detects vibration upon increase and decrease in engine rpm. The knock sensor generates a voltage based on this vibration. Should this voltage go outside a calibrated level a DTC will set. Knock sensor circuit short to GND
Knock sensor circuit short to PWR
Damaged knock sensor
Damaged PCM
Knock sensor circuit open
A knock sensor voltage greater than 0.5V with the key ON and engine OFF indicates a hard fault.
P0340 - Camshaft Position (CMP) Sensor Circuit Malfunction The test fails when the PCM can no longer detect the signal from the CMP sensor. CMP circuit open
CMP circuit short to GND
CMP circuit short to PWR
SIG RTN open (VR sensor)
CMP GND open (Hall effect sensor)
CMP misinstalled (Hall effect sensor)
Damaged CMP sensor shielding
Damaged CMP sensor
Damaged PCM
Harness routing, harness alterations, improper shielding, or electrical interference from other improperly functioning systems may have intermittent impact on the CMP signal.
P0350 - Ignition Coil (Undetermined) Primary/ Secondary Circuit Malfunction Each ignition primary circuit is continuously monitored. The test fails when the PCM does not receive a valid IDM pulse signal from the ignition module (integrated in PCM). Open or short in Ignition START/RUN circuit
Open coil driver circuit
Coil driver circuit shorted to ground
Damaged coil
Damaged PCM
Coil driver circuit shorted to VPWR
P0351 Through P0360 - Ignition Coil A through J Primary/ Secondary Circuit Malfunction Each ignition primary circuit is continuously monitored. The test fails when the PCM does not receive a valid IDM pulse signal from the ignition module (integrated in PCM). Open or short in Ignition START/RUN circuit
Open coil driver circuit in harness
Coil driver circuit shorted to ground
Damaged coil
Damaged PCM
Coil driver circuit shorted to PWR
P0400 EGR Flow Failure (outside the minimum or maximum limits) The EEGR system is monitored once per drive cycle during steady state conditions above 48 mph . The test will fail when a malfunction is detected by PCM calculations indicating the EGR flow is less or greater than expected. EEGR valve stuck open or closed
Connector to EEGR not seated
EEGR motor windings shorted or open circuited
No power to EEGR
Harness open or shorted to power or ground
Vacuum signal to MAP restricted or leaking
MAF sensor signal erroneous
Damaged PCM
Carbon build up in EEGR valve seat area
One or more sensor not responding or out of range
All of the following sensors input data to the PCM for proper operation of the EEGR system: ECT, CPS, IAT, MAF, TP, MAP. Any DTC relating to these sensors must be resolved prior to addressing
P0400 code.
P0401 - EGR Flow Insufficient Detected The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum. Vacuum supply
EGR valve stuck closed
EGR valve leaks vacuum
EGR flow path restricted
EGRVR circuit shorted to PWR
VREF open to D.P.F. EGR sensor
D.P.F. EGR sensor downstream hose off or plugged
EGRVR circuit open to PCM
VPWR open to EGRVR solenoid
D.P.F. EGR sensor hoses both off
D.P.F. EGR sensor hoses reversed
Damaged EGR orifice tube
Damaged EGRVR solenoid
Damaged PCM
Perform KOER self-test and look for DTC P1408 as an indication of a hard fault. If P1408 is not present, look for contamination, restrictions, leaks, and intermittents.
P0402 - EGR Flow Excessive Detected The EGR system is monitored for undesired EGR flow during idle. The EGR monitor looks at the DPF EGR signal at idle and compares it to the stored signal measured during key ON and engine OFF. The test fails when the signal at idle is greater than at key ON engine OFF by a calibrated amount. EGR valve stuck open
Plugged EGR vacuum regulator solenoid vent
Plugged EGR tube
Slow responding D.P.F. EGR sensor
Damaged DPF EGR sensor
Improper vacuum hose connection
Plugged vacuum hoses
EGRVR circuit shorted to ground
Damaged EGR vacuum regulator solenoid
Damaged PCM
A DPFEGR PID reading that is greater at idle than during key ON and engine OFF by 0.5 volt or a rough engine idle, may indicate a hard fault.
P0403 EEGR Electric Motor Windings Or Circuits To The PCM Shorted Or Open The EEGR system is continously monitored to check the 4 EEGR motor coils, circuits, and the PCM for opens, shorts to power and ground. If a malfunction is detected the EEGR system will be disabled and additional monitoring will be suspended for the remainder of the drive until the next drive cycle. EEGR motor windings open
Connector to EEGR not seated
Open circuit in harness from PCM to EEGR
Open circuit in PCM
Short circuit in EEGR motor
Short circuit in harness from PCM to EEGR
Short circuit in PCM
If an intermittent condition is suspected the most effective methoid of wiring fault isolation is to use the wiggle test methoid while measuring for shorts and open circuits.
P0411 - Secondary Air Injection (AIR) system upstream flow See DTC P1411
P0412 - Secondary Air Injection System (AIR) circuit malfunction The PCM attempts to control when air is injected in the exhaust. The DTC indicates a Secondary Air injection system AIR circuit fault. AIR circuit open
AIR bypass solenoid fault
Damaged PCM
AIR circuit short to power
Solid state relay fault
Damaged AIR pump
The AIR circuit is normally held high through the AIR bypass solenoid and SSR when the output driver is off. Therefore, a low AIR circuit indicates a driver is always on and a high circuit indicates an open in the PCM.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1) Indicates Bank 1 catalyst system efficiency is below the acceptable threshold Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler/tailpipe assembly
Retarded spark timing
Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
P0430 - Catalyst System Efficiency Below Threshold (Bank 2) Indicates Bank 2 catalyst system efficiency is below the acceptable threshold. Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler/tailpipe assembly
Retarded spark timing
Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
P0442 - EVAP Control System Leak Detected (Small Leak) The PCM monitors the complete EVAP control system for presence of a small fuel vapor leak. The system failure occurs when a fuel vapor leak from an opening as small as 1.016 mm (0.04 inch) is detected by the EVAP running loss monitor test. After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
Small holes or cuts in fuel vapor hoses/tubes
Canister vent solenoid stays partially open on closed command
Damaged, cross-threaded or loosely installed fuel filler cap
Loose fuel vapor hose/tube connections to EVAP system components
EVAP system component seals leaking (EVAP canister purge valve, fuel tank pressure sensor, canister vent solenoid, fuel vapor control valve tube assembly or fuel vapor vent valve assembly)
P0443 - EVAP Control System Canister Purge Valve Circuit Malfunction The PCM monitors the EVAP canister purge valve circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified purge duty cycle by PCM command. VPWR circuit open
EVAP canister purge valve circuit shorted to GND
Damaged EVAP canister purge valve
EVAP canister purge valve circuit open
EVAP canister purge valve circuit shorted to VPWR
Damaged PCM
Monitor EVAPPDC PID and voltage between EVAP canister valve signal and PWR GND in output test mode with key ON engine OFF (or in key ON engine RUNNING mode). EVAPPDC PID at 0% and voltage less than 1.0 volts (or EVAPPDC PID at 100% and voltage less than 0.5 volts) indicates a hard fault.
P0451 - FTP Sensor Circuit Noisy The fuel tank pressure changes greater than 14 inches of H 2 0 in 0.10 seconds. Intermittent open or short in the FTP sensor or the FTP sensor signal.
Monitor FTP PID and does it change from above 15 inches of H 2 0 to below a minus (-) 15 inches of H 2 0 often in 1.0 minute.
P0452 - FTP Sensor Circuit Low Voltage Detected The PCM monitors the EVAP control system FTP sensor input signal to the PCM. The test fails when the signal average drops below a minimum allowable calibrated parameter. Contamination internal to FTP sensor connector
Damaged PCM
FTP circuit shorted to GND or SIG RTN
Damaged FTP sensor
FTP V PID reading less than 0.22 volt with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0453 - FTP Sensor Circuit High Voltage Detected The PCM monitors the EVAP control system FTP sensor input signal to the PCM. The test fails when the signal average jumps above a minimum allowable calibrated parameter. FTP circuit open
VREF shorted to VPWR
Damaged PCM
FTP circuit shorted to VREF or VPWR
SIG RTN circuit open
Damaged FTP sensor
FTP V PID reading greater than 4.50 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.
P0455 - EVAP Control System Leak Detected (No Purge Flow or Large Leak) The PCM monitors the complete EVAP control system for no purge flow, the presence of a large fuel vapor leak or multiple small fuel vapor leaks. The system failure occurs when no purge flow (attributed to fuel vapor blockages or restrictions), a large fuel vapor leak or multiple fuel vapor leaks are detected by the EVAP running loss monitor test with the engine running (but not at idle). After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube
EVAP canister purge valve stuck closed
Damaged EVAP canister
Damaged or missing fuel filler cap
Insufficient fuel filler cap installation
Loose fuel vapor hose/tube connections to EVAP system components
Blockages or restrictions in fuel vapor hoses/tubes (items also listed under disconnections or cracks)
Fuel vapor control valve tube assembly or fuel vapor vent valve assembly blocked
Canister vent (CV) solenoid stuck open
Mechanically inoperative fuel tank pressure (FTP) sensor
Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank.
P0456 - EVAP Control System Leak Detected (Very Small Leak) The PCM monitors the complete EVAP control system for the presence of a very small fuel vapor leak. The system failure occurs when a fuel vapor leak from an opening as small as 0.508 mm (0.020 inch) is detected by the EVAP running loss monitor test. Very small holes or cuts in fuel vapor hoses/tubes.
Loose fuel vapor hose/tube connections to EVAP system components.
EVAP system component seals leaking (refer to Possible Causes under DTC P0442).
P0457 - EVAP Control System Leak Detected (Fuel Filler Cap Loose/Off) A fuel tank pressure change greater than a minus (-) 7 inches of H 2 0 in 30 seconds has occurred after refueling; or there is excessive purge (fuel vapor) flow greater than 0.06 pounds per minute. Fuel filler cap not installed on refueling (storing continuous memory DTC) and "check Fuel Cap" light may also be illuminated.
Fuel filler cap missing, loose or cross-threaded.
Check for missing fuel filler cap or integrity of the cap. If OK, clear continuous memory DTCs and re-initiate EVAP Emission Running Loss Monitor Drive Cycle.
P0460 - Fuel Level Sensor Circuit Malfunction The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified fuel fill percentage in the fuel tank. Empty fuel tank
Fuel pump (FP) module stuck open
Incorrectly installed fuel gauge
Damaged instrument cluster
CASE GND circuit open
FLI shorted to VPWR
Damaged PCM
Overfilled fuel tank
Fuel pump (FP) module stuck closed
Damaged fuel gauge
FLI circuit open
FLI circuit shorted to CASE GND or PWR GND
CSE GND shorted to VPWR
Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.
P0500 - Vehicle Speed Sensor (VSS) Malfunction Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS), anti-lock brake system (ABS) control module, generic electronic module (GEM), or central timer module (CTM). If the engine rpm is above the torque converter stall speed (automatic transmission) and engine load is high, it can be inferred that the vehicle must be moving. If there is insufficient vehicle speed data input, a malfunction is indicated and a DTC is set. On most vehicle applications the malfunction indicator lamp (MIL) will be triggered when this DTC is set. Open in VSS+/VSS- harness circuit.
Open in TCSS signal or TCSS signal return harness circuit.
Short to GND in VSS harness circuit.
Short to GND in TCSS harness circuit.
Short to PWR in VSS harness circuit.
Short to PWR in TCSS harness circuit.
Open or short in the vehicle speed circuit(s) (VSC) between the PCM and appropriate control module.
Damaged VSS or TCSS.
Damaged wheel speed sensors.
Damaged wheel speed sensor harness circuits.
Damage in module(s) connected to VSC/VSS circuit.
Damage drive mechanism for VSS or TCSS.
Monitor VSS PID while driving vehicle. This DTC is set when the PCM detects a sudden loss of vehicle speed signal over a period of time. If vehicle speed data is lost, check the source of where the vehicle speed input originates from: VSS, TCSS, ABS, GEM or CTM. Note: On some MSOF applications, VSS and TCSS PID can be monitor. However if no TCSS PID is available and VSS PID is zero, TCSS circuitry frequency must be checked for loss of sensor signal. If another vehicle electronic module has generated the P0500 and the vehicle does not receive its vehicle speed input from one of the above mention sources (VSS, TCSS, ABS, GEM or CTM). Check the PCM for Output Shaft Speed Sensor (OSS) DTCs. On OSS applications the PCM uses the OSS to calculated the vehicle speed. If no OSS DTCs are found check for correct PCM configuration. Check PCM configuration for correct tire size and axle ratio.
P0501 - Vehicle Speed Sensor (VSS) Range/ Performance Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. This DTC is set the same way as P0500, however the malfunction indicator lamp (MIL) is not triggered. Refer to possible causes for P0500.
Refer to diagnostic aids for P0500.
P0503 - Vehicle Speed Sensor (VSS) Intermittent Indicates poor or noisy VSS performance. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS), anti-lock brake system (ABS) control module, generic electronic module (GEM), or central timer module (CTM). Noisy VSS/TCSS input signal from Radio Frequency Interference/ Electro-Magnetic Interference (RFI/EMI) external sources such as ignition components or charging circuit.
Damaged VSS or driven gears.
Damaged TCSS.
Damaged wiring harness or connectors.
Malfunction in module(s) or circuit connected to VSS/TCSS circuit.
After market add-on.
Monitor VSS PID while driving vehicle, check for intermittent vehicle speed indication. Verify ignition and charging system are functioning correctly.
P0505 - Idle Air Control System Malfunction The PCM attempts to control engine speed during KOER self-test. The test fails when the desired rpm could not be reached or controlled during the self-test. IAC circuit open
VPWR to IAC solenoid open
IAC circuit shorted to PWR
Air inlet is plugged
Damaged IAC valve
Damaged PCM
The IAC solenoid resistance is from 6 to 13 ohms.
P0552 - Power Steering Pressure (PSP) Sensor Circuit Malfunction The PSP sensor input signal to the PCM is continuously monitored.The test fails when the signal is open or shorted to ground. PSP sensor damaged
SIG RTN circuit open or shorted
VREF circuit open or shorted
PSP sensor signal circuit open or shorted
Damaged PCM
The DTC indicates the PSP sensor circuit is open or shorted to ground.
P0553 - Power Steering Pressure (PSP) Sensor Circuit Malfunction The PSP sensor input signal to PCM is continuously monitored. The test fails when the signal is shorted to power. PSP sensor damaged
SIG RTN circuit shorted to power
VREF circuit shorted to power
PSP sensor signal circuit shorted to power
Damaged PCM
The code indicates the PSP sensor circuit is shorted to power.
P0602 - Control Module Programming Error This Diagnostic Trouble Code (DTC) indicates programming error within Vehicle ID block (VID). VID data corrupted by the scan tool during VID reprogramming
Using the scan tool, reprogram the VID block. If PCM does not allow reprogramming of the VID block, reflashing PCM will be required.
P0603 - Powertrain Control Module KAM Test Error Indicates the PCM has experienced an internal memory fault. However there are external items that can cause this DTC. Reprogramming
Battery terminal corrosion
KAPWR to PCM interrupt/open
Loose battery connection
Damaged PCM
If KAPWR is interrupted to the PCM because of a battery or PCM disconnect, DTC can be generated on the first power-up.
P0605 - PCM read only memory (ROM) error Indicates the PCM ROM has been corupted. An attempt was made to change the calibration.
Module programming error.
Damaged PCM
Reprogram or update calibration.
Reprogram VID block (use as built data).
Check for other DTC's or drive symptoms for further action.
P0703 - Brake Switch Circuit Input Malfunction Indicates PCM did not receive a brake pedal position (BPP) input. Open or short in BPP circuit
Open or short in stoplamp circuits
Damaged PCM
Malfunction in module(s) connected to BPP circuit. (Rear Electronic Module [REM] Windstar and LS6/LS8 or Lighting Control Module (LCM) Continental and Town Car.
Damaged brake switch
Misadjusted brake switch
Check for proper function of stoplamps. Follow correct Self-Test procedures, refer to Section 2 of Quick Test.
P0704 - Clutch Pedal Position Switch Malfunction When the clutch pedal is depressed the voltage goes to low. If the PCM does not see this change from high to low the DTC is set. CPP circuit short to PWR
Damaged CPP switch
CPP circuit open in the SIGRTN
Damaged PCM
When depressing the CPP switch the voltage should cycle from 5.0V down.
P0720 - Insufficient input from Output Shaft Speed sensor The output shaft speed sensor inputs a signal to the PCM, based on the speed of the output shaft of the transmission. The PCM compares this signal with the signal of the VSS or TCSS and determines correct tire size and axle gear ratio. OSS sensor circuit short to GND
OSS sensor circuit short to PWR
OSS sensor circuit open
Damaged OSS sensor
Damaged PCM
Verify sensor signal output varies with vehicle speed.
P0721 - Noise interference on Output Shaft Speed sensor signal The output shaft speed sensor signal is very sensitive to noise. This noise distorts the input to the PCM. Wiring misrouted
After market add-on
Wiring damaged
Wiring insulation wear
Check routing of harness.
Check wiring and connector for damage.
P0722 - No signal from Output Shaft Speed sensor The output shaft speed sensor failed to provide a signal to the PCM upon initial movement of vehicle. Damaged OSS connector
Damaged OSS sensor, or not installed properly
Harness intermittently shorted or open
P0723 - Output Shaft Speed sensor circuit intermittent failure The output shaft speed sensor signal to the PCM is irregular or interrupted. Harness connector not properly seated
Harness intermittently shorted, or open
Harness connector damaged
OSS sensor damaged, or not installed properly
Verify harness and connector integrity
Verify OSS sensor proper installation
P0812 - Reverse Switch (RS) input circuit malfunction The DTC indicates that the voltage is high when it should be low. Transmission shift not indicating neutral while in KOEO Self-Test
RS circuit short to PWR
Damaged reverse switch
RS circuit open or short to SIGRTN
Damaged PCM
Check RS PID while exercising shift lever in and out of reverse.
P1000 - Monitor Testing Not Complete The on board diagnostic II (OBD II) monitors are performed during the OBD II Drive Cycle. The DTC will be stored in continuous memory if any of the OBD II monitors do not complete. Vehicle is new from the factory
Battery or PCM had recently been disconnected
An OBD II monitor failure had occurred before completion of an OBD II drive cycle
PCM DTCs have recently been cleared with a scan tool
PTO circuit is shorted to VPWR or B+ or PTO is on during testing
The DTC does not need to be cleared from the PCM except to pass an inspection/maintenance test.
P1001 - KOER Not Able To Complete, KOER Aborted This Non-MIL (Malfunction Indicator Lamp) code will be set when Key On Engine Running (KOER) Self-Test does not complete in the time intended. Incorrect Self-Test Procedure.
Unexpected response from Self-Test monitors.
rpm out of specification.
Rerun Self-Test following QT1 in Section 3 , Symptom Charts, STEP 1: PCM Quick Test.
P1100 - Mass Air Flow (MAF) Sensor Intermittent The MAF sensor circuit is monitored by the PCM for sudden voltage (or air flow) input change through the comprehensive component monitor (CCM). If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory diagnostic trouble code (DTC) is stored. Poor continuity through the MAF sensor connectors
Poor continuity through the MAF sensor harness
Intermittent open or short inside the MAF sensor.
While accessing the MAF V PID on the scan tool, lightly tap on the MAF sensor or wiggle the MAF sensor connector and harness. If the MAF V PID suddenly changes below 0.23 volt or above 4.60 volts, an intermittent fault is indicated.
P1101 - Mass Air Flow (MAF) Sensor Out of Self-Test Range The MAF sensor circuit is monitored by the PCM for an out of range air flow (or voltage) input. If during key ON engine OFF the air flow voltage signal is greater than 0.27 volts the test fails. Likewise, if during key ON engine running, an air flow voltage signal is not within 0.46 volt to 2.44 volts, the test fails. For voltage to air flow gm/sec conversion, GO to Pinpoint Test DC and refer to Voltage To Mass Air Flow Conversion Table. Low battery charge
MAF sensor partially connected
MAF sensor contamination
PWR GND open to MAF sensor
MAF RTN circuit open to PCM
Damaged MAF sensor
Damaged PCM
A MAF V PID reading greater than 0.27 volts (KOEO) or a MAF V PID reading outside the 0.46 volt to 2.44 volts range (KOER) indicates a hard fault.
P1112 - Intake Air Temperature (IAT) Sensor Intermittent Indicates IAT sensor signal was intermittent during the comprehensive component monitor. Damaged harness
Damaged sensor
Damaged harness connector
Damaged PCM
Monitor IAT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.
P1114 - Intake Air Temperature 2 Circuit Low Input Indicates the sensor signal is less than Self-Test minimum. The IAT2 sensor minimum is 0.2 volts. Grounded circuit in harness
Improper harness connection
Damaged sensor
Damaged PCM
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P1115 - Intake Air Temperature 2 Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The IAT2 sensor maximum is 4.6 volts. Open circuit in harness
Sensor signal short to power
Improper harness connection
Damaged sensor
Damaged PCM
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P1116 - Engine Coolant Temperature (ECT) Sensor Out of Self-Test Range Indicates the ECT sensor is out of Self-Test range. Correct range is 0.3 to 3.7 volts. Overheating condition
Malfunctioning thermostat
Damaged ECT sensor
Low engine coolant
Damaged harness connector
Damaged PCM
Engine coolant temperature must be greater than 10°C (50°F) to pass the KOEO Self-Test and greater than 82°C (180°F) to pass the KOER Self-Test.
P1117 - Engine Coolant Temperature (ECT) Sensor Intermittent Indicates ECT circuit became intermittently open or shorted while engine was running. Damaged harness
Damaged sensor
Damaged PCM
Damaged harness connector
Low engine coolant
Monitor ECT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.
P1120 - Throttle Position (TP) Sensor Out of Range Low (RATCH too Low) The TP sensor circuit is monitored by the PCM for a low TP rotation angle (or voltage) input below the closed throttle position through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) remains within the calibrated self-test range but falls between 3.42 and 9.85% (0.17 and 0.49 volt), the test fails. TP circuit with frayed wires
Corrosion on TP circuit connectors
VREF open to TP sensor
VREF short to SIG RTN
TP sensor loose pins
A TP PID (TP V PID) between 3.42 and 9.85% (0.17 and 0.49 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.
P1121 - Throttle Position (TP) Sensor Inconsistent with MAF Sensor The PCM monitors a vehicle operation rationality check by comparing sensed throttle position to mass air flow readings. If during key ON engine running self-test the comparison of the TP sensor and MAF sensor readings are not consistent with calibrated load values, the test fails and a diagnostic trouble code is stored in continuous memory. Air leak between MAF sensor and throttle body
TP sensor not seated properly
Damaged TP sensor
Damaged MAF sensor
Drive vehicle and exercise throttle and TP sensor in all gears. A TP PID (TP V PID) less than 4.82 % (0.24 volt) with a LOAD PID greater than 55% or a TP V PID greater than 49.05% (2.44 volts) with a LOAD PID less than 30% indicates a hard fault.
P1124 - Throttle Position (TP) Sensor Out of Self-Test Range The TP sensor circuit is monitored by the PCM for an out of range TP rotation angle (or voltage) input. If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) reading is less than 13.27% (0.66 volt) or greater than 23.52% (1.17 volts), the test fails. Binding or bent throttle linkage
TP sensor not seated properly
Throttle plate below closed throttle position
Throttle plate/screw misadjusted
Damaged TP sensor
Damaged PCM
A TP PID (TP V PID) reading not between 13.27 and 23.52% (0.66 and 1.17 volts) in key ON engine OFF or key ON engine running indicates a hard fault.
P1125 - Throttle Position (TP) Sensor Intermittent The TP sensor circuit is monitored by the PCM for sudden TP rotation angle (or voltage) input change through the comprehensive component monitor (CCM). If during the last 80 warm-up cycles in key ON engine running the PCM detects a TP rotation angle (or voltage) changes beyond the minimum or maximum calibrated limit, a continuous diagnostic trouble code (DTC) is stored. Poor continuity through the TP sensor connectors
Poor continuity through the TP harness
Intermittent open or short inside the TP sensor
While accessing the TP V PID on the scan tool, lightly tap on the TP sensor or wiggle the TP sensor connector and harness. If the TP V PID suddenly changes below 0.49 volt or above 4.65 volts, an intermittent fault is indicated.
P1127 - Exhaust Not Warm Enough, Downstream Sensor Not Tested The HEGO monitor uses an exhaust temperature model to determine when the HO2S heaters are cycled ON. The test fails when the inferred exhaust temperature is below a minimum calibrated value. Engine not operating long enough prior to performing KOER self-test.
Exhaust system too cool.
Monitor HO2S Heater PIDs to determine their ON/OFF state. DTC P1127 will be present if the exhaust is not hot.
P1128 - Upstream Oxygen Sensors Swapped from Bank to Bank (HO2S-11-21) The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated. Crossed HO2S harness connectors (upstream).
Crossed HO2S wiring at the harness connectors (upstream).
Crossed HO2S wiring at the 104-pin harness connectors (upstream).
P1129 - Downstream Oxygen Sensors Swapped from Bank to Bank (HO2S-12-22) The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated. Crossed HO2S harness connectors (downstream).
Crossed HO2S wiring at the harness connectors (downstream).
Crossed HO2S wiring at the 104-pin harness connectors (downstream).
P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit. Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)
A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.
P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1132 - Lack of HO2S-11 Switch, Sensor Indicates Rich A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1137 - Lack of HO2S-12 Switch, Sensor Indicates Lean The downstream HO2S sensors are forced rich and lean and monitored by the PCM. The test fails if the PCM does not detect the output of the HO2S in a calibrated amount of time. Pinched, shorted, and corroded wiring and pins
Crossed sensor wires
Exhaust leaks
Contaminated or damaged sensor
P1138 - Lack of HO2S-12 Switch, Sensor Indicates Rich See DTC P1137
P1150 - Lack of HO2S-21 Switch, Fuel Trim at Limit See DTC P1130
P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1152 - Lack of HO2S-21 Switch, Sensor Indicates Rich A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1157 - Lack of HO2S-22 Switch, Sensor Indicates Lean See DTC P1137
P1158 - Lack of HO2S-22 Switch, Sensor Indicates Rich See DTC P1137
P1168 - Fuel Rail Pressure Sensor in Range But Low The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below a calibrated value. Low fuel pressure
Damaged FRP sensor
Excessive resistance in circuit
Low or no fuel
A FRP PID value below 551 kpa (80 psi) indicates a failure
Low or no fuel
A FRP PID value greater than 896 kpa (130 psi) indicates a failure
