trouble code P0420

[BigKid]

I have a 2000 T/A Ws6 with 13K . I'm getting a P0420 left bank cat performing below threshold code. the car sat for 6 months just before I bought it and I'm still running out the old gas as I mix in new. Any ideas,

Could it be the O2 after cat?
Old gas
or is it the cat?

Seems to run fine, but I havent really had it on a beat run since I got it.

I would appreciate any ideas.

[2001NBMZ28]

If you don't think it's clogged or rattling (coming apart inside) I'd give it some time. You can try clearing the code, swap the rear 02's side to side to see if the code changes too. Remember cats are covered under the federal emissions warranty for 8yrs/80K.

[Hurley711]

Me dealer replaced both cats AND both O2s when my P0420 code came up. IOf I were you I would go in and have them replace them while the code is still there, you're covered under the 8/80k law so why not get the stuff replaced for free?

[BigKid]

Thanks for the info, I cleared the code but haven't taken it out for a ride.
As soon as it comes up again, assuming it will, I'll get it to the dealer.

I hadn't thought about the 8/80k law.


Thanks again!