I have a P0420 code that sets off and not able to pass smog I started looking into it. After watching my downstream O2 fluctuate from .1-.4 before cleaning, now after cleaning its at .1-.8. The code still comes back right away. Also I noticed I am able to look at the "Readiness codes" on the programmer. It gave me one false code, a P0441 (Evaporative Emission Control (EVAP) System Incorrect Purge Flow), P2501, and a P0803 (1-4 Upshift Skip Shift Solenoid Control Circuit Malfunction). Is it possible the EVAP might have something to do with this P0420 code?
I got the P0420 the same. I look the code have 3 problems. #1.O2 sensor #2.Mass airflow sensor #3.Catalytic convertor I fix the temporary problem by use the scanguage to scan and clear the code.
