Rollmodel

About a month or two ago the service engien light in my 01 ws6 came on, i had it scanned and it threw two codes, one was 0420 and the other 1416, i replaced both air check valves(1416), and the light went off until about a few days ago, i had it scanned again and it threw 0420, what is that code, and what needs to be done, anyone?

JEB Garner

DTC P0420 Catalyst System Low Efficiency Bank 1

Rollmodel

what does that mean?

robertbartsch

Bad 02 sensor(s), bad cat converter or both.

GM is required to replace a bad cat for nada if the mileage is 60K or less. You don;t have any mods; right?

Bo White

iTrader: (59)

I was throwing 0430 which is bank 2 so I just had gomer delete it

Rollmodel

I have an SLP catback exhaust, would this void the warranty on the cats?

King Nothing

iTrader: (9)

if it's stock then no if it's aftermarket than probably, clal you local chevy dealership and by the way the federal emissions warranty is bewtween 2 years or 24k and 8 years or 80k