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Had to change my Focussport intake back to stock from CA smog test. Passed the test just fine. Next day I started it and ran for less than a minute then got a CEL. Found out it was a P0141 which means "O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)" I did search and got some info about it but no real resolution. Should I just take it to a ford dealer and pay way too much for them to check it out and fix it? Thanks in advance.

I do plan on buying an AEM intake so I won't have to change back to stock for emission or getting pulled over. Gotta love Cali
 

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bank 1 sensor 2 is the rear sensor... did you maybe run with it disconnected for a bit? if not, 9 out of ten times, it's in the o2 sensor itself. the heater circuit is the pre-heat function of the o2 (o2 doesn't read right until it is heated up to normal temp) This code takes one full drive cycle to set, so it showind up on the second start makes sense. If it happened right after connecting/disconnecting an O2, check the connectors for poor fit/bent pins or corrosion.
 

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bank 1 sensor 2 is the rear sensor... did you maybe run with it disconnected for a bit? if not, 9 out of ten times, it's in the o2 sensor itself. the heater circuit is the pre-heat function of the o2 (o2 doesn't read right until it is heated up to normal temp) This code takes one full drive cycle to set, so it showind up on the second start makes sense. If it happened right after connecting/disconnecting an O2, check the connectors for poor fit/bent pins or corrosion.

Thanks for the help, I've never disconnected the o2..so I can only assume that it failed on me?

btw you've got PM~
 

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Thanks for the help, I've never disconnected the o2..so I can only assume that it failed on me?
That'd be my gut reaction. You could pull up a wiring diagram and follow thru everything checking for a break in the circuit, but in my entire career, I've only seen 2 or 3 failures that WEREN'T the actual O2, unless someone was recently messing with it. So if it were me (and I had an understanding parts guy) I'd just toss a Rear O2 into the car and clear the codes, drive for a few days and see.
 

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hmmm... PO134 is an upstream O2 code... you sure you haven't messed with any wiring lately? (don't worry about P1000 that's a incomplete test code... means your car hadn't completed all self tests when you accessed it... common and wont affect anything)

Now I wonder if you might want to actually chase stuff down, given that both O2's are throwing codes... 134--inactivity B1S1, and 141--heater circuitB1S2
 

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Discussion Starter #11
Thanks for all your help. I checked the MAF. Looked good and was connected fine. Since you're so helpful, got any ideas as to what to do next? Got a part number I can ask for at the Ford parts counter? Thanks again.
 

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I doubt your MAF would set an O2 code. especially a heater circuit code.
check where the harness splits off to the O2 sensors and follow the wires down to each sensor... its pretty close to the intake (below and to the right facing the engine) maybe when you were installing the intake the harness got moved and pinched or burned.

I don't know any part numbers, but if your 02 harnesses are ok after checking them, i'd gamble and buy a rear o2 sensor.
 

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I've seen those front O2 sensor harnesses get pinched between the transaxle and bulkhead under hard acceleration during a hard 1-2 shift, when running the stock rear engine mount.
 

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I had the same P0141 code come up during an emissions test, a while back ago I had to unplug my IMRC box under the driver side fender. I was having some problems with with it and when I read up on some forums I guess alot of people where saying that my IMRC box was making noise because my DSI clip broke off or something, they said to just unplug it and the worst that would happen is my gas milage would slightly go bad. My question is am I getting this Code PO141 because my IMRC box is unpluged or is it just my O2 Bank 1 Sensor 2 that is bad and needs to be replaced?

Thanks, any help is greatly appriciated.
 

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After having replaced both front and rear O2s, it's gonna be the O2 that you have to replace 99% of the time. They're not that expensive. But as others have said, check the wires leading to the O2 and see if there are any breaks. The IMRC should not affect O2 one bit. Entirely unrelated. And the DSI "clip" you're referring to is actually a lever and if you want your DSI function back, get the billet lever and save yourself some headache.
 
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