ok, so I have a 02 SS and last Monday I started up the car and heard a rattle noise. The noise was loud and changed when I blipped the throttle. So I figured that it was something with the exhaust and had my company's mech take a look at it. He called me to inform me that the passenager side cat had come apart inside and was causing the noise. I was told me that the cat is made up of an outer shell and inner housing. He said that the inner part had broke loose from the outer. Causing the inner to bounce around from the exhaust gases. I was hoping it was something minor like a lose bolt or something. He told me the replacement cat would cost about $750 but I should be able to go to the dealer for replace. Federal law states that cat have to last 8 years or 80k miles(plus I have a bumper to bumper 10/100K warrenty through chevy) . On Tuesday, I then got a CEL. On Saturday I went to the dealer with the problem and explained that the car had already been looked at and that as of Tuesday I also had a CEL. 2hrs later, my car was washed and I was given a service ticket stating that the CAT and related gaskets were replaced and the CEL was related to the cat problem. This Monday morning, I start up the car and the same rattle of last Monday is back. On the way into work that morning my CEL reappeared. The odd thing is in both cases the constent rattle will go away but a vibration can still be heard.

Questions: What are the chances of two cat's going bad within a week? From my point of view, I feel as if all the dealership did was wash my car and reset the CEL. But, they did give me a service ticket showwing a repair was made. I cant got back to the dealership with this attude tho because that lead to problems quicker, IMO. What would you do? Would you go back to the dealer and say the problem is back? Or would you go to a different dealer and try to get them to fix it? Also, my mpg is really ****tie this week. Would my CEL caused by the cat be causing the pcm to dump fuel? This week so far I have about 220 miles on my tank and I'm almost on empty. With my commute I average about 18-20mpg. So far this week I'm about 14-15mpg.

 

I'd take a look under the car and look at the exhaust threads/cat to see if if looks like it was changed, maybe even stop by AZ and see if your're still throwing P0430 too (if so, leave it stored). Depending on what you find your choice is to bring it back, or try another dealer. Guess it's possible they installed a faulty cat - but I doubt if a good one would deteriorate that quick.

 

I agree. Only a very small chance that a brand new GM cat would fail that quick.