Haddixj

iTrader: (1)

01 camaro SS has code p420 cat eff low, googled it and found most saying its the rear O2 sensor so I bought a denso sensor and chaned it. We live in California so we smogged it and it passed the dyno portion with hydrocarbons being 18 and 10 where 51 and 35 are failing. So I dont think the cat is actually bad. So what else is there to try? I found online people saying an exhaust leak may cause it.
So what else is there to try? I need to get this thing smogged but dont just want to throw more parts at it.

im-not-guilty

iTrader: (4)

15 years at the gm dealership and I have yet to see a p0420 that has not needed a cat

RPM WS6

iTrader: (3)

The cat is obviously working well enough that you can still pass the sniffer, since you already did. So at this point, might as well just tune out the rear O2 codes and then you'll be able to pass the OBD scan as well.

Haddixj

iTrader: (1)

That is what I was wondering if I get the rear O2 tuned out can I still pass the CA smog stuff. I know they plug into the computer and do some sort of a functional test of the monitiors and that is what it failed on because they werent ready dut to the codes being erased.

So anyone in CA know if the rear O2's are removed did you still pass smog? Also who in Sacramento area can do it? I dont want to buy HP tuners just for this and about what is the going rate for something like this to be done?

RPM WS6

iTrader: (3)

I think most shops would cover rear O2 deletions under their "basic tune" package, which is usually around ~$150 or so.

You might want to start a thread in the western regional section for questions that are specific to CA smog processes.