TT Surgeon

I never get CELs with my current FS setup.

rmira

I'll be taking the car in next week, I'll let everyone know what the dealer said. Thanks for everyone's input.

sunset

I have the fabspeed exhaust and have the same problem. Codes are supposed to be related to the high-flow cats, I am told. Not sure if this applies to you or not.....

drbf

I have the same problem after installing two different sets of FS cats. Error code P0420 'catalyst system efficiency below threshold bank 1' All of the O2 sensors have been replaced by dealer. I will call Joe at FS they are excellent to deal with and back their products.

rmira

I ended up not taking the car in because the CEL turned off on his own. I don't know why.

jhbrennan

Did you clear the codes - I think they remain in the DME/ECU until cleared??

TT Surgeon

Even if you clear the codes it will recycle every 30 miles and 'rescan'.

E55AMG

trying to figure out if these codes are exhaust related: P2099 P2097 Bank 1 Bank 2. Lambda correction behind catalyst