Bad IAT Sensor?? - Maintenance and Repair Forum

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Bad IAT Sensor??
Monday, February 07, 2005 6:14 PM
I have a 2002 2.2l "2200" Cavalier. Lately I've been having the "TRAC OFF" light come on just about every time I start the car when cold. It comes on within the first few minutes. Once the light is on, It is on for the duration of the trip /drive cycle, whatever you want to call it. When I restart the car the next time (as long as the car is still warm), it's still on and will stay on until I drive the car a few miles. After about 2-3 miles of driving it turns off. I've read in other post that the IAT sensor will cause things like the "TRAC OFF" light to come on and will mess with the air/fuel mixture. I checked the computer for codes, it showed "P0132 pending" but only when the "trac off" light is on. When it turns off the code disappears. Has anybody else had or experienced the same thing,and was IAT the cause? Any help would be appreciated. Thanks.

Re: Bad IAT Sensor??
Monday, February 07, 2005 6:40 PM
the iat is a 10 dollar part, just replace it if you think that it is the cause. i couldn't tell ya about the problem though, i don't have the facy trac control on my 99
Re: Bad IAT Sensor??
Wednesday, February 09, 2005 7:04 PM
Well I replaced the IAT sensor last night. Started the car this morning and the stupid "trac off" light came on again. I've already done both O2 sensors, new plugs and wires, new IAT sensor and nothing seemed to do the trick. It doesn't seem to affect the performance much while the light is on (other then the fan running while the light is on), but it's just the idea that something is wrong and I want to fix the problem. Is there anything that I might have overlooked or forgot to check?
Re: Bad IAT Sensor??
Tuesday, February 22, 2005 9:36 AM
Conditions for clearing the code:

  • The Malfunction Indicator Lamp will turn off after three consecutive ignition cycles in which the diagnostic runs without a fault.
  • A history DTC will clear after 40 consecutive warm up cycles without a fault.
  • The code can be cleared by using the scan tool.



The DTC P0132 or rich exhaust is most likely caused by one of the following items:

  • Fuel Pressure
  • - The system will go rich if fuel pressure is to high. The PCM can compensate for some increase, but not too much.
  • Leaking Injector
  • - A leaking or malfunctioning injector can cause the system to go rich.
  • Electronic Ignition (EI) Shielding
  • - An open ICM reference low circuit may result in a EMI or induced electrical noise. The PCM looks at this noise as a Crankshaft Position (CKP) sensor pulses. The additional pulses result in a higher than actual engine speed signal. The PCM then delivers too much fuel causing the system to go rich. The engine tachometer will also show higher than actual engine speed which can help in diagnosing this problem.
  • MAP sensor
  • - An output that causes the PCM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor electrical connector - will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the MAP sensor is disconnected.
  • Pressure regulator
  • - Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the fuel pressure regulator.
  • TP sensor
  • - An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating.
  • O2S 1 contamination
  • - Inspect the O2S 1 sensor for silicone contamination from fuel or the use of improper RTV sealant. The O2S 1 sensor may have a white powdery coating and this will result in a high but false voltage signal (rich exhaust indication). The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem.




Re: Bad IAT Sensor??
Tuesday, February 22, 2005 11:53 AM
I had the same problem with my 99. I replaced the Sensor and then a couple days later the trac light went off. Most likely that was your prob.
Re: Bad IAT Sensor??
Tuesday, February 22, 2005 8:27 PM
Well, I took the 02 sensor out and it looked like it was coated with some soot or something like that around the base. It was really loosely threaded in there(didn't need a socket to get it out). I cleaned it off with just a rag and put it back in(tight this time). Second trip after a cold start, the light turned off and hasn't come back on. That seemed to do the trick hopefully. Now I have the dreaded "PO420"! If it ain't one it's another! Thank everybody.
Re: Bad IAT Sensor??
Tuesday, February 22, 2005 8:29 PM
Thanks everybody.
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