I just wanted to ask a question that's related to this but since I've seen that there are a million threads on P0420 I didn't want to start another one! I had a P0420 pulled for catalyst efficiancy in bank one, so I ran a few cans of berryman's, but it stayed, so now I've put on mileliminators, thinking that it would fix the problem, but when I started the car, the check engine light is still on. I haven't had the code read to see if it is still P0420, but before that code there was no check engine light and it's never had a problem before, so... I was just wondering if the P0420 code could still be coming up because one of the oxygen sensors was bad? Thank you for any help! Sorry if I sound like a noob
