Been a while since ive posted but i got my 01 t/a on the road it was a salvage title and i repaired it, passed salvage inspection, i got my temp plates (CT) so i could get it emmisioned. I fixed the problem i knew, The knock sensor plugs was torn, cleared the codes fixed it drove about 120 mile went to emmisions. I failed beacause the computer did not complete all of its rediness tests day i failed on the way home my scanner said it completed all of them but then the ses light came on, p0420 Catalyst System Efficiency Below Threshold (Bank 1), figured out that most likely it is the CAT, the rear 02 sensor, or wiring. Put it on a lift wiring seemed good. I know the cats are going beacause when the car is idling i hear a rattle and it seems like the same rattle i heard hitting the y pipe under the cats with a mattot. (like they were falling apart and parts if the cats were sitting in the y pipe)

My main question(thanks for listening to the rambling) the rear 02 sensor on bank 1 is reading bad (thats why its setting the code for the cat) weather its the 02 sensor or the cat, would a 02 sim on that sensor fix the problem? im planning on a full exhaust over the winter thats why i dont want to spend money on stock parts, i just want it to pass emmisions so i can get rid of the temp plate

 

I doubt it's a bad post-cat 02 for P0420 - 99% of the time it's the cat itself. GM extended the warranty on them to 10 years/120K on the 00-02 cars. Contact a dealer and see what they say, don't know if a salvage title car qualifies for free replacement? Wouldn't mention it. IMO an 02 simm would just mask the problem, if it's coming apart internally you need to gut them or replace them.

 

Ive heard about the warrenty, ive got about 58000 on the clock so its still under, but there is a dent on the bottom of the bank 1 cat, and the pipe is hit under the cat on bank 2 so wouold a damged cat still be under warrenty, i doubt it, im gonnna call gm tomarrow. but i still think maybe the 02 sim on there would make it read right so the p04020 would go away and i could get through emmisions

 

Yes.... the purpose of the "sim" is to eliminate the P0420 code. Can be hard to find, since the EPA fined Casper $70,000 for manufacturing them.