P0420Post the CEL code.
Consider the fact that this code can also be (and most often is) caused by:P0420
Would require additional engine mapping.Turbo XS High Flow Catalytic Converter pipe.
Okay, should I just replace the rear O2 sensor?Consider the fact that this code can also be (and most often is) caused by:
1. Gross exhaust leak prior to the rear O2 sensor
2. Malfunctioning rear O2 sensor
I'd start there.
This
Would require additional engine mapping.
Start in the order I posted.Okay, should I just replace the rear O2 sensor?