JayinAZ

I have an '05 Coupe with 36k miles. I bought it 2 weeks ago and the only mod on the car is a Borla catback. A few days after buying the car the check engine light came on with code P0420. I brought it back to the dealer where I bought it and they said it needs a new cat with a cost of $778. I don't like that plan.

Can I just get a tune and have that code tuned out without any adverse effects? I kind of have my doubts that the cat is really failing with such low miles but if it really is a bad cat and I left it on and just tuned the code out, would that be a bad thing?

What if I did replace the pass. side cat and used say a much cheaper magnaflow cat, but left the stock cat on the driver side? Would that be ok?

Anyway, any help with the cat code and possible options would be greatly appreciated.
Thanks all!

RicK T

Disclaimer: This probably has nothing to do with your situation so take it with a grain of salt BUT it might be worth checking with a Chev dealer. Since your 8/80 emission warranty is over anything you do will be on your dime but a good dealer might be willing to talk to you about it for free.

This was a situation with the '08-'09 Z06's but may be applicable in some way to you:

http://forums.corvetteforum.com/c6-z...-cat-code.html

SSWEET

Might try the tech forum,

not08crmanymore

Um,do they not have laws in Arizona? A cat is something that should be under any and all used car warranties and are in fact covered for 8 years or 80,000 miles or something like that by a federal warranty..putting all that aside for a minute..you bought the damn car a week ago and the dealer isn't going to fix it?? I'd be taking that bitch right to court! Did you smell rotten eggs at all?When cats go bad,that's the smell.

P0234

I'd swap the O2 sensors before I touched the cat. When the O2s fail, they make the computer think the cats are failing. Has the dealer or you measured the cat temps to see if they are actually firing?

RicK T

What I was getting at but forgot to mention is, maybe the (or a) previous owner modded the car, put headers on with no cats and a custom tune. When they put it back to stock to sell maybe they got the factory tune wrong and it just needs to be reflashed.

Do you know anything about the car's history? Did you get a GMVIS report to show what repairs and maintenance GM has done to it?

Tropicana

It might be worth getting an OBD scanner and if you're up to it, some software that allows for logging. It might be something as simple as a vacuum leak.

JayinAZ

The car is at the dealership where I bought it fixing the other little issues I found in my first few days of ownership at their cost. They made it very clear that this was an "as is" car and was 9 years old now. Despite declining the several thousand dollar warranty, they are fixing the other things including the column lock issue which they "fixed" about 2 weeks prior to me buying it. After being stuck twice in 2 weeks, they decided to fix it and cover their repair work. Of course I am currently getting the "cannot duplicate problem" now speel which is frustrating. The P0420 code with check engine light decided to stop showing up the morning I dropped the car off a week ago. Luckily that code is stored so my guess is they automatically just said it needs a new pass. side cat. The dealer is a Cadillac dealership so they should at least kind of know all GM vehicles, but they said they are speaking to the GM tech people (I don't remember exactly what they called it) about the column lock to find a solution since they spent about $800 replacing the column lock and ignition switch when the previous owner traded the car in.
I did get all the GM records on the car and it shows the column lock fix and some other minor stuff but nothing about the cats.
I am not smelling any foul odor from the exhaust. I don't know when the catback was installed but I do know it is a 2 owner car and the last owner had it for 4 years and put on less than 1k miles. I don't know if the car sitting for so longer made a difference for these problems or not.
At some point I will talk to a well known tuner in the area but I'd really like to know if he can just tune the code out without ramifications.
And can I get 1 Magnaflow cat and have 1 stock cat?
Please keep the comments coming.... I won't even ask about making an MP3 disc that plays for at least another week. LOL!

VET4LES

A bad cat is very rare. I'd replace the 02 sensor first.

raspyc6

wife just got 430 code, bank 2 in 2009 Acadia. I went to Advanced Auto in Temple Terrace to have OBD read by sweet Sharon and at the end of the day it was likely nothing. For direct injection engines I hear any hiccup/misfire will throw an o2 sensor code before or after cats. Wonder if c7 will do this being DI?

ruxvette

[QUOTE=VET4LES;1587498934]A bad cat is very rare. I'd replace the 02 sensor first. [/QUOTE
Try driving the car HARD...heavy throttle, long trip, etc...to see if the cat will clean out. Happened to me.

AORoads

36K miles, 2 weeks old (to you), at Cad dealer...hmm, I'm thinking like Rick above, and the post just above, rux's. Some Cad dealer techs usually know quite a bit about Corvettes, so this is an odd one, too.

As to one cat, since you have a tuner in mind, ask them for their opinion on that one. But I'd try the O2 sensor suggestion first--or maybe, suggest it to the Cad tech working on your car????? See what he says. Realize you may be working, but an early morning stop at the dealer and talk w. the tech, not the Service Advisor, may be of help to him/car.

Not incl. the second owner who had it for years and racked up very low miles, I have a feeling something was done to this car earlier by one of the owners, probably the first one. Or it's just a car that's acting up after nine or so years.

I'd say you're coming to (or may be at) the point where you will have to take it somewhere where they know C6s, work on them all the time, and will have to pay out of pocket to get the car right. So, maybe before that happens you can get the Cad dealer who sold you the car to do some or most of the replacement (like 02, column lock, ignition sw., etc.) and then take the diagnostics with you to "the specialist."

tennblkc6

if they have previously replaced the column lock and its still acting up you may want to try the column lock eliminator.
as far as the cat is concerned I wouldn't hesitate to replace it with a magnaflow. I had 2 installed in my off road xpipe. however, I do have my downstream o2s turned off in my tune. found this quote:

Guinzu

At near $800, go for aftermarket exhaust...like longtubes.

shawnaj7731

I have a set of cats stock manifolds they are good if you want it you can have it just pay the shipping.

not08crmanymore

There is/was a tsb or bulletin and a retune issued years ago by GM regarding the column lock issue.Look up in FAQ section for it and bring it to them.They are not corvette knowledgeable,trust me on that. Very few Chevy dealers are and they are the ones that sell them,imagine a non corvette selling dealership such as Caddy.

Corvettinator

Uh, dude, that's really not an accurate summary of used car laws.

All Magnuson-Moss requires is that warranties - or disclaimers of them - are written in clear language. "As is" means what it says, unless you can prove fraud or breach of duty of good faith under the UCC.

IAALBNYL.

JakeC6Racing

Last thing I would do is pay that much for a new cat. There are plenty of guys selling used ones in the market place for significantly less if thats what it came down to

JayinAZ

Well it has been almost a month and the check engine light hasn't come on again, nor is it throwing any codes. I don't know what happened or why it seems to be all better now. Hopefully I didn't just jinx myself by saying this.

VET4LES

Good news.