P0420 - is it the cat or O2 sensor gone bad?
Thread Starter
On The Tree
Joined: Nov 2001
Posts: 147
Likes: 0
From: Athens, GA
P0420 - is it the cat or O2 sensor gone bad? Just got this code last night and pulled it today. Cleared it and it came right back on a few minutes later. I'm not really interested in O2 simms because I'm trying to sell the car. But I need to get this straightened out the cheapest way possible.
How can I tell if it's a cat gone bad vs. an O2 sensor gone bad? I always thought the rotten-egg smell was the giveaway for a dead cat, but there is none.
Thanks.
Dan
How can I tell if it's a cat gone bad vs. an O2 sensor gone bad? I always thought the rotten-egg smell was the giveaway for a dead cat, but there is none.
Thanks.
Dan
TECH Resident
Joined: Jan 2002
Posts: 754
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From: USA
Re: P0420 - is it the cat or O2 sensor gone bad? P0420 TWC System Low Efficiency Bank 1
If the 02 was bad it would be tripping DTC errors.
With your CM scanner do the 02 tests and see what it reports. Here is example of good versus flaky, in this case crappy headers causing air being sucked in and effecting O2s
<img src="http://teamzr1.com/pcmecm/02badgood.gif" alt=" - " />
If the 02 was bad it would be tripping DTC errors.
With your CM scanner do the 02 tests and see what it reports. Here is example of good versus flaky, in this case crappy headers causing air being sucked in and effecting O2s
<img src="http://teamzr1.com/pcmecm/02badgood.gif" alt=" - " />
