TomcatMF

Three years ago my car through P0420 and P0430 codes. I took it to the local Chevy dealer and they determined the cats were bad and replaced both of them. No problems again for a long time until the P0430 code came back again last week. I took it first to a local mechanic I trust to look at it and he determined that the cat is bad. So I contacted the dealer about this and they weren't very helpful, saying that they only covered replacement parts for one year.

I have since contacted GM customer service and started a case with them. I don't think it's right to expect me to shell out a huge sum for a very expensive part, that is in reality supposed to last at least 7-10 years. I have only put about 30,000 miles on the car since the cats were replaced.

GM told me the first thing I need to do is take the car to a dealership to verify the problem, and then they would see what kind of "financial assistance" they could provide.

If I'm expected to replace the cats every couple of years as "maintenance" then I will likely be parting ways with this otherwise excellent automobile.

And I live in the People's Republic of California, so removing the cats is not an option.

Apocolipse

Make sure your valve guides are not dumping oil down into them

freddyvette

Step one move out of commie fornication

Step two remove cats

???

Step three profit.

All trolling aside, are you using ZDDP additives? Are you tuned? Take a picture of all 8 spark plugs and see if you can read them. When your cats were replaced, did they replace both downstream sensors? Has your mechanic used a scanner to see what the readings are?

grcor

Some of us like to breath clean air. Also it's nice to look up and see blue sky and not grey!

Dan_the_C5_Man

Plus-one on keeping cats, regardless if the government needs to tell you it's the tight thing to do or not, it is...

There was an issue with the PCM calibration IIRC, whereby overly sensitive values were causing false triggers from the rear O2's (the only way to determine the status of the exhaust processing by the cats). I would hope they have swapped in new O2's by this point.

The solution in the false-postive case was an ECU update. I belive there is a TSB on it.

Sox-Fan

Your post doesn't say anything about your car.

Anyhow, somewhere in this forum there are posts about a TSB for a software update on certain years that addresses repeat catalytic convertor codes. It might apply to your car, might not. You don't put anything in your post to go by........

here is one of them
https://www.corvetteforum.com/forums...-cat-code.html

I had my '08 flashed and it fixed the issue.


edit-- Dan beat me to it.

freddyvette

Durien512

OP - Dan is right, there is a GM bulletin that addresses the issues with false 420 &430 codes. I just took mine to the dealership, had the parameters updated, no more codes, cats are fine.

Durien512

Here is a link to read...

https://www.corvetteforum.com/forums...0420-code.html

2k Cobra

The dealer's replacement warranty of one year is wrong for Cats. The following is copied from Google relating to the laws. California and Fed

New aftermarket converters are required to have a 5 year/50,000 mile warranty on the converter shell and end pipes. They are also required to be warranted to meet EPA's emission performance standards for 25,000 miles when the vehicle is properly used and maintained.

Good luck..

TomcatMF

My car is bone stock 2007 with 90K miles on it. No tune or anything done to it. It is my DD, but I put about 10K miles a year on it, and I change the oil and filter myself when the car tells me it's time to do it. I just replaced the air filter with an OEM air filter last fall too.

I first replaced the cats just over 3 years ago when the P0420 and P0430 codes both came up. I took it to the local Chevy dealer and they said both cats needed to be replaced, and they were. The dealer says they did the reprogramming when the cats were replaced the last time.

I will take it to the dealer again and have them take a good look at it. I would definitely like them to get to the bottom of this. If there is another underlying issue causing the cats to fail prematurely, I definitely want it addressed.

I will post an update once I know more.

ssbowtie1

Are you sure they updated your calibration? There is a TSB for this issue for those model years. See post #17: https://www.corvetteforum.com/forums...ter-issue.html

RichieRichZ06

John, you win the internet for the day and are 100% correct except for the 50k mile part on replacement converters.

To the OP, your dealer should replace them at no charge, assuming that you purchased them both when they previously failed and the dealership installed them at that time. GM will warranty replacement cats that are installed at the GM dealer for 25,000 miles and as far as I know, there are no limits on time. Tell your dealer to check page 108 of the GM parts policies and procedures manual.... You should be good to go, assuming you've put less than 25k miles on the car since you have them installed 3 years ago.

RichieRichZ06

One quick question, but do you run ANY type of octane boosters or fuel additives at all?

TomcatMF

No additives. I only put Shell or Chevron premium gas in it, (91 octane is the highest available pump gas in California)

RichieRichZ06

OK. We've seen several cats lose their efficiency and cause those same codes from using additives/octane boosters.

AzDave47

Dealer replaced a cat the first time. The 2nd time I got the code I took a copy of the TIL referenced in the link in, they reprogrammed it and the code never came back. Print out the TIL and take it to the dealer for proper fix.

Apocolipse

Is there a good line of aftermarket ones?

AzDave47

OEM cats are fine, just the dealers mistakenly replace them rather than do the software update.

s2000Mi

My guess is that they arent checking everything that could cause the cats to fail. 420 code means the cats are bad but cats dont fail on their own (usually).