96 lumina Code P0420

[rodneys]

Took car to Auto Zone and they checked for codes,came up P0420.The print out read that the Catalyst system efficiency for bank 1 is below thresholdfor the current engine conditions. (Bank 1 identifies the location of cylinder #1,while bank 2 identifies the cylinder on the opposite bank).Still seems to run ok,could it be some kind of sensor? Thanks Alot,

[GMMerlin]

What has happened is the catylist has lost its efficency.
If you have less than 80000 on your car, take it to the dealer....the converter is covered under warranty for 8 years and 80k miles...replacement is no cost to you.

[rodneys]

Thanks GM, I guess I'll have to take it to Dealer.Thanks again,, Car has 96,000 miles on it.

[PoliceCarToTaxiCab]

yeah...my 99 just started throwing this same code and like a dummy I just started changing oxygen sensors needlessly because I didn't really take the time to try and comprehend "catalyst below threshold", when it mentioned "bank 1" I automatically assumed that it meant the oxygen sensor before the converter was bad itself. Than, to further demonstrate how little I actually think about things... I changed the oxygen sensor after the converter thinking it was the problem. Then I kept wondering why in the world my check engine light kept coming on. I'm about to put a higher capacity universal converter on my car. Anyone have any problems doing this? I'm hoping to get a little more power as well as better fuel mileage... atleast that's what I was told would happen. It's a shame cuz I only have 65,000 miles on mine but I'm a second owner.

[foureyedbuzzard]

Originally Posted by PoliceCarToTaxiCab

I'm about to put a higher capacity universal converter on my car. It's a shame cuz I only have 65,000 miles on mine but I'm a second owner.

Your bad cat is covered under EPA mandated warranty even though you are not the original owner!
The CAA(Clean Air Act) requires an 8-year or 80,000 mile warranty on the major emissions control components such as the catalytic converter.

[frstrtdblzr]

I have a 97 3.1 and I had that same code come up in my obd 2 diagnostinc tester and I had the cat replaced for 290 dollars and the code instatnly went away.