04 ls6 p0420

Hi,
My 2004 LS V6 (64k miles) is giving a P0420 code, is there a way to determine whether it is the cat or the O2 sensor?

From what I have read, there is a common issue with valve cover gaskets leaking, compromising COPs, therefore causing misfire which could lead to a premature cat failure. Did the V6 have the common COP issue or was that just the V8? I have had the car since 53k miles and I don't believe it has ever misfired. The only issues I have noticed are a strong sulfur/rotten egg smell under heavy acceleration and a faint burning oil smell when the heat is on. (The second seems consistent with oil leaking onto the exhaust manifolds, but there has been no drop in the oil level)

Also, since P0420 is bank 1, is there a way to get to those COPs without removing the plenum? If not, are there instructions online somewhere for removing the plenum?

Thanks in advance for any help and advice,
Frank

Federal Emission warranty for perfromance maybe cover 8yr/80k miles for your catalytic converter.

How much will Lincoln service charge todo a install?

Start with getting the paper work, from the inspection station, that it failed.