Hello,


I have a 2009 BMW 328 xi coupe ( manual ) has roughly 163000kms, and my check engine light turned on- brought it to my mechanic and the error message he was receiving was to replace the Oxygen Censor ( Bank 2, Censor 1 )I got the part replaced with him, he cleared the codes with his device, was able to drive for 20-30kms, and then the engine light turned back on again! I continued driving for another day and then the CEL turned off again... the next day, back on!I brought the car back to him and he ran the diagnostic, and he was getting the same error message again, said for me to leave him the car tomorrow to further investigate what it could beAny thoughts on how to proceed/what could be the issue? These things arn't cheap and I hope I didn't replace that for nothing if the issue is coming from somewhere elseAlso I know i'm not being very specific with the exact error codes, I can get them tomorrow and post them here if it helps.

Please help.

I didn't find the right solution from the Internet.

References:-
http://www.bimmerfest.com/forums/showthread.php?t=1256260
example of case study

Thanks