Here it is:
P0420 Catalyst System Low Efficiency

I did some searching, but didn't find much for the 2000 +

Basically what I want to know is with 125,000 miles on the car, what do you think..... O2 sensor, or Cat?

Thanks in advance.

my 02 only has 85000 and it was the cat had to replace it cost me like 165

Did you find this link? Not Bonnie specific...

http://www.obd-codes.com/trouble_cod...old-bank-1.php

This code means that according to the data, O2 Bank 1 sensor (In front of Cat) vs O2 Bank 2 (behind Cat) the difference is not within the specified value.

Usually this would indicate a bad catalytic, however it is possible that the rear O2 sensor has failed. The odds are on the catalytic.

Thanks.

Is there a way to check the O2 sensors with a multimeter?




EDIT

one more thing, would this cause a lack of power? of course a plugged cat would, but I am wondering if just a bad O2 sensor or this code alone would cause a lack of power.

also update here from this one: http://www.bonnevilleclub.com/forum/...810&highlight=


Took the car up to the stealership today and got it scanned. We were quoted $82.00, but to our amazement, only cost us $42.00


well, turns out that the cat is "partially" blocked. and the stearing wheel position sensor is bad. Just like everyone said


So, my question is, if we go with a Magnaflow Hi-Flow cat is it going to set off any codes?

also, does anyone have the correct part number handy for the cat I need ( magnaflow ) and also the steering wheel position sensor. I have looked at gmpartsdirect and rockauto and can't seem to find it :?

I haven't been able to locate a part number for the position sensor at AllData, and from this TSB, it would appear as if there are several possibilities.
Steering Position Sensor
It could be called steering angle sensor, also.

ok, I have been looking and I must be blind or something, because I can't seem to find the cat I need, or the steering wheel position sensor :(


We need the cat pretty badly, I was driving the car today and I floored it and noticed quite a bit of black smoke behind me....

If anyone knows the part #* of can link me to where to buy the parts from, I would REALLY appreciate it.

They dont seem to have a direct fit cat for the 2000+ bonnevilles, the closest thing i can find is...
http://www.car-sound.com/02product/d...niversal=94806

I am looking for the Magnaflow hi-flow cat... not sure if that is :?