Bad Catalytic Converters?

[scoer84]

I have a 99 camaro ss, 112k. Stock headers and Y-pipe. SES light came on with P0160 and P0140 (no activity detected for both post cat sensors). I proceded to change both sensors, and the light went off for about a week. Now the light is back on, the guy at Advanced says the new codes are P0420and P0430. Do you think the cats are bad?

I was wondering if the combination of original pre-cat o2 sensors and new post cat o2 sensors would cause this if the pre cat sensors are so old they could be not be quick enough for the new post cat sensors? It seems a coincidence that the low efficiency code comes on for both banks right after installing new post cat sensors for both banks.

Thanks

[mrr23]

clear the codes and see if they come back. of they do, then get them replaced under warranty if you are under 8 years or 80,000 miles at the dealer.

[scoer84]

so you think it is definatly the catalytic converter? Since I am well over 80,000 miles I doubt gm will give me warranty coverage. Guess I just have to decide if I want to buy new cats or o2 sims.

[mrr23]

with the cats being bad, o2 simms aren't going to cure your problem. they will continue to clog up until they won't flow anymore.

[96z28]

cats are covered under warranty even if you're not original owner. I received a letter from GM for both my camaro and my hawk stating that they would replace the cats if i had any issues with them

[yellowv]

He has 112,000 miles GM isn't going to do anything for him for free. Good excuse to get LT's and ORY Either that or look at the classifieds here. I am sure there are plently of guys getting rid of complete stock Y pipes pretty cheap.

[scoer84]

I like the idea of getting headers.. maybe I'll shop around for a complete package that includes a Y pipe. I'd still have to have cats though, I'm in NC and they do a visual verification of emissions equipment during the state inspection.