P0420 Cat or O2 Sensor?
Thread Starter
Teching In
Joined: Jun 2009
Posts: 9
Likes: 0
From: Chicago, IL.
P0420 Cat or O2 Sensor? I popped a SES code P0420 on my 99 WS6. Took the it to Autozone to run the code and showed P0420, Basically a bad driver side cat.
Question that I have is it most likley the cat that is failed or the rear O2 sensor?
If it is the cat can I get away with running a Magnaflow Cat on the drivers side with the stock left on the pass without screwing anything up?
Thanks!
Question that I have is it most likley the cat that is failed or the rear O2 sensor?
If it is the cat can I get away with running a Magnaflow Cat on the drivers side with the stock left on the pass without screwing anything up?
Thanks!
Teching In
Joined: Jun 2005
Posts: 36
Likes: 0
From: Dallas, GA
Its the cat that is bad. You can try to run the magnaflow but its going to fail again in probably less then a year. Just remove both cats and run o2 sims or have it tuned and be done with the whole thing.
