[wardamnbmw]

Hello all,

I'm new to this forum, but am looking for help on some recurring error codes I have been receiving on my 2011 328i. I have no modifications whatsoever, the car is completely stock.

I have commonly recurring 2C31 and 2C32 exhaust too lean codes

I also have 2c2b "mixture too fat" codes and 2c6c "signal leaner than expected" codes occurring less frequently.

I have attached the codes at freezeframe for reference of when they are occurring and seem to occur at cold start or at cruisng rpms.

I have done a variety of troubleshooting thus far. I have checked the MAF sensor and MAP sensor, they seem to be functioning well.

I have done an at home smoke test to look for vacuum leaks and could not find any. I have checked the intake boot for cracks and removed the throttle body and checked o ring.

I also got frustrated and threw one Bosch pre cat o2 sensor in to see if it solved any codes, which it did not. The funny thing is that I did get a "lambda sensors switched" code one day, but it rarely shows as I have cleared the codes multiple times. I checked the rear sensors and it seems that they are in the right banks with the silver cord in bank 2 and the black cord in bank 1, as the wiring harnesses will not allow you to plug the opposite sensor in. The voltages I am seeing on inpa seem ok for all sensors, so what am I missing here?

Would my next plan of attack be to check the DISAs or remove intake manifold and check ccv? or to possibly check for fuel delivery issues?

Sorry for the long winded post, but I have had it up to here with these issues. The car runs great, no misfires, but I can smell gasoline when standing outside of car when idling. Not exactly sure if it is coming from exhaust, but I think so.

[F31B48]

I would suggest doing a smoke test on the intake to check for air leaks. Could be a split PCV diaphram or hose.

[wardamnbmw]

I did try that with a siphon pump and a cigar. I couldn't see any leaks, however, I know I wasn't quite using the ideal tools for the job.

[wrongmark]

Did you solve this as I’m having similar problems and have bought all these bosch O2 sensors but have yet to fit them.