I threw a SES light the other night while just sitting at a stoplight. I had AutoZone read it & it revealed 4 codes. All of them were "Catalyst Efficiency Below Threshold" (I think P0430 & P0420, or something close to that)

My car only has 13,000 miles on it. The mods are as follows: SLP Blackwing Lid, K&N Filter, SLP CNC-Ported Heads (stock cam).....that's it.

Is it possible that my cats are bad already?? I'm just looking for any input/thoughts before I take it to the dealer.

TIA!
-Andy

 

The same thing happened to me my ses light came on and then it would stay on for a few days then go off for a few then come back on so i took to dealer and they said it was 1 or both of my cats so they replaced only 1 of them and ses light stayed off for about a month then came back on so i went back to dealer and they said it was the other cat so they replaced that 1 and that was about 2 weeks ago and my light is still off as of now.
so that prob is what wrong with yours mine is still under warrenty so it didnt cost me nothing.

Reply back if you have any questions.

 

You have a bad cat. To be more specific, it's probably the driver's side cat.

There is a service bulletin out for late 2000 and early 2001 production F-Bods about the bad driver's side cat and this code.

My 2001 Z28, built October 2000, had this problem and they replaced the driver's side cat under warranty. After it was totalled, I bought a 2001 WS6, built in October 2000, and it had the exact same problem. This time the dealer went ahead and replaced both cats under warranty for me.

If your car is under warranty, have them replace the cats. If it isn't under warranty, you can either install O2 simulators, or you can find someone that replaced their exhaust and see if they will give you their cats, or at least sell them cheap.

I see "free cats" all the time, and no ... I'm not talking about furry things that meow. Most folks just give away their stock exhaust components after they upgrade. At least, they do around here.

 

Thanks alot guys!! This was exactly the type of info I was looking for.

-Andy