New answers tagged p0420
0
90% of the time a P0420 is a bad cat converter. If you want to throw in a new upstream O2 sensor, fine. But you'll probably be replacing the cat converter anyway. See this post on P0420
https://ricksfreeautorepairadvice.com/p0420-is-it-the-catalytic-converter-or-the-oxygen-sensor/
Top 50 recent answers are included
