P1129 ODB Code

[denik]

My check engine light came on about a week ago. I finally got a chance to go over to AutoZone to see what was the cause of the check-engine light by using their ODB. The ODB meter showed a P1129 error code and said something about "fuel air metering."

After using the ODB meter, I tried opening the gas cap and reclosing it. After about 10 minutes of driving, the check engine light went away. Is the P1129 error code related to the gas cap not being completely closed? Or do I still need to worry about this error code popping up again?

[Richard Hamilton]

I assume yours is an early car with DME5.2.2 (non-eGas), as the P1129 code is only listed for this DME version. The OBD2 manual (and the OBD2 code list here on the forum - A GOOD REASON FOR CONTRIBUTING) shows it as:

P1129

Oxygen Sensing Adaptation Area 2 (Cylinders 4 - 6) - Lean Threshold

There is a reference in this section of the manual which says "If DTC P0445 (EVAP canister purge valve - short to ground) is stored in the memory, correct this fault first. An open EVAP canister purge valve can lead to the lean threshold being reached." I am not sure if opening the gas cap could have released a sticking purge valve, but I suppose it is a possibility.

Attached is the section of the manual - HTH.

P1127_P1129.pdf

Edited December 31, 2005 by Richard Hamilton

[denik]

Thanks for the info Richard.

I was able to get the Check Engine light to go away. I opened my gas cap, and closed it again, making sure it went through several clicks. I then drove for about 15 minutes, and the light went away. I suppose that it's possible the problem just corrected itself or the gas cap wasn't closed tightly enough.