P0420 Volkswagen -

Question

Have a P0420 code and I replaced the cat 4 months ago for the same code. What might I be missing here. Could I have a 2nd bad cat?

Thank you garguy1.

Answer 1

Hi there,

It is very possible if you used an aftermarket converter it's bad already. Also, a bad rear O2 sensor can cause the code or a poorly running engine. i would clear the code at least once and drive the car, if the code comes back then the rear O2 sensor should be checked for a problem.