SES code P0420 (suggestions on replacement cats)
Thread Starter
Instructor
Joined: Jun 2003
Posts: 101
Likes: 0
From: Austin TX
SES code P0420 (suggestions on replacement cats)
I recently had my LT4 dyno'ed and the tuner disabled the Random Misfire detection to squelch the SES code 43. The next day I got SES and suspected he may have accidently re-enabled during all the trial and error tuning. It turns out it was SES code 420 for bank 1 catalytic converter. I don't see any relationship between the dyno runs and this code. A search for the code 420 did not turn up any instances here. Any suggestions on what to replace the stock cats with. Or, could this be a false reading? I am not running headers but may be persuaded down the road.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
The forward O2 detects the exhaust condition as it is coming out of the engine, the rearward detects the condition after the cat, the computer expects it to improve. If not, then the cat COULD be bad.
I like the idea of checking that 2nd O2... It is the cheap fix.
How many miles on the car? In 1996, I think the warrantee is 50k miles - if you are under that, GM owes you a new cat.
I like the idea of checking that 2nd O2... It is the cheap fix.
How many miles on the car? In 1996, I think the warrantee is 50k miles - if you are under that, GM owes you a new cat.
Thread Starter
Instructor
Joined: Jun 2003
Posts: 101
Likes: 0
From: Austin TX
Thanks Bogus, I missed it by 20K miles. I will research how to test the 02 sensor. But, I would like to hear some recommendations on aftermarket high flow cats. Particualarly, which has the best fitment for C4's.
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Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
emissions are now 8/80 or even 10/100, it's a federal mandate. I am just not sure when it started.
testing the O2? if they are original, replace them all. they ain't expensive.
as for high flow cats? Check Random Technologies or Car Sound (part of Magnaflow).
Neither have direct fit for the LT1/4, tho.
testing the O2? if they are original, replace them all. they ain't expensive.
as for high flow cats? Check Random Technologies or Car Sound (part of Magnaflow).
Neither have direct fit for the LT1/4, tho.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
As far as I know, 1995 is covered by the 8/80K Fed Emissions Warranty - at least it covered a new PCM on the wife's '95 Gran Prix 2 years ago. I thought it was only CA at first - but CA is only 7/70K - and in fact that had just expired at the time I had the PCM replaced. The Fed regs are better. If your Dealer is denying it, file a complaint with the EPA.
