[Greycamaro19]

Hi all. I bought a 2019 Camaro 1SS new and After about 500 miles I had a Flowmaster American Thunder axle-back system installed and then had the secondary catalytic converters removed after about 2,500 miles. I put about another 1,200-1,500 miles on it after the secondary cat delete (a combination of city and highway driving). I also took it to the drag strip twice where I made about 6 passes each time – no problems and no check engine light. Back in the spring, after the car had been sitting in my garage for a couple of weeks, I started it up to take it for a drive and the Service Stabilitrack light came on and it would barely run – idled very rough and black liquid substance was blowing out the tailpipe. Shortly, the check engine light (CLE) came on too.

I took it to the dealer where I purchased it and they discovered two of the injectors had failed. They saw that I had removed the secondary catalytic converters and said I had voided the entire warranty on the car but that they would just not report that the secondary cats were removed to GM and go ahead and fix the injectors under warranty (I know this isn’t accurate, but I didn’t get into that with the guy). They also said it had a small exhaust leak where the secondary cats had been removed. Anyway, they fixed the injectors and after about 50 miles of driving, the check engine light came back on.

I took it back to the dealer and they said it was throwing the P0430 code which translates to “catalyst system efficiency below threshold (Bank 2).” This was a different guy from whom I dealt with the first time, and he was not giving me an attitude about the secondary cat delete but did tell me that the warranty would be void on the emissions system (which I knew) and that there was probably a tinny exhaust leak sucking air which causes the O2 senser to read incorrectly. He told me to take it back to my exhaust guy and have the leak fixed. Long story short, I ended up taking it to two exhaust shops who checked for leaks (didn’t find one but welded it up more anyway) and then a local performance shop I use and trust who dropped the entire exhaust system and checked it out. Each time, after driving about 50 miles, the CLE came back on and threw the same P0430 code every time.
Finally, the performance shop concluded it must be the absence of the secondary cats causing it to throw the code. He put some aftermarket high flow secondary cats on it and again after about 50 miles, the CEL came back on. He then checked the O2 sensors and said they were heavily corroded with carbon, likely from the injectors failing. He put in new O2 sensors he ordered from GM and the light still came back on!

I do not know what to do next. If I take it back to the dealer, I know they will say it needs the stock secondary converters (which I don’t have), but I don’t believe that is the issue. If the light would have come on within a few miles of initially deleting them, then sure, I could believe that. But it’s too much of a coincidence that it only started simultaneously with the injector failure and hasn’t been right since. I’m thinking it has to be connected to the injectors failing and not the secondary cat delete – they were off for 8+ months and I drove the car 1,200 – 1,500 miles and had it on the drag strip twice with no issues. If paying the $2,000 + for new, stock secondary cats would fix it, I’d do it, but I do not believe it will fix it so I’d like to have an idea of what else I could maybe try before I have to go deal with the dealer. Any thoughts from you guys would be greatly appreciated.

[gmw0181]

You have an exhaust leak to get that code. I had one too. I fixed the exhaust leak and was done