Another CEL thread I know. I just made my downpipe catless this weekend and are now throwing two codes. I know the first one is for the O2 sensor, and the 2nd one is fuel trim bank one- system too lean. Is this common after getting catless dp? I added the O2 extension on my downpipe so it's not in the mainstream. I also have infiniboost tune, just an fyi. Any help?

Nevermind, my exhaust gasket was crooked causing my car to sound weird and throw the codes, all fixed now.

 

did u ever get the code again the p2096 fuel trim bank one system too lean cause i get it all the time now

 

nope, sure haven't. The O-ring gasket from the manifold to the downpipe was like 2" off center, I corrected it and the codes went away.

 

wow maybe i will try that thanks

 

Well that makes sense. The misaligned gasket was an oxygen leak. Too
Much oxygen was brought into the exhaust via venturi effect and the post cat otwo sensor read an oxygen rich state, meaning too lean. The cause was operator error, as usual, though, giving creedence to the theory that we make 90% of our own problems.