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mmaxwell
06-04-2004, 11:06 AM
My SES light came on yesterday so I took my car to autozone and had them read the codes. The code came up as # 1 bank catylist below efficiency level. Does anyone know exactly what that means? The guy at autozone said it meant the catylitic converter was bad, but why would it say # 1 bank? the 3400 has both banks connected and there's only one cat. converter. Any help is greatly appreciated. Thanks in advance.

Hexx
06-04-2004, 01:28 PM
My SES light came on yesterday so I took my car to autozone and had them read the codes. The code came up as # 1 bank catylist below efficiency level. Does anyone know exactly what that means? The guy at autozone said it meant the catylitic converter was bad, but why would it say # 1 bank? the 3400 has both banks connected and there's only one cat. converter. Any help is greatly appreciated. Thanks in advance.

I'm not 100% sure on this, but changing the O2 sensor might help. Has it ever been changed and also, how many miles are on the car?

Helmut
06-04-2004, 02:39 PM
I'm also going to venture a guess. You've got 2 O2 sensors in your car. . .1 before the cat, 1 after. I'm guessing that the sensors are your "bank 1" and "bank 2"

Hexx
06-04-2004, 05:59 PM
I'm also going to venture a guess. You've got 2 O2 sensors in your car. . .1 before the cat, 1 after. I'm guessing that the sensors are your "bank 1" and "bank 2"
Yeah that's what I was thinking too but I don't know as much about O2 sensors as some people here would so I can't say for sure that this is the issue....it might be though.

RedGT2004
06-04-2004, 09:36 PM
Do you know the exact code?

mmaxwell
06-05-2004, 12:57 PM
No I don't know the exact code but I'll probably try replacing the O2 sensor.

Mike Jung
06-05-2004, 09:39 PM
I'm guessing code: P0420 - Catalyst system efficiency below threshold

Your O2 sensor after the cat. is picking-up that the cat is not cleaning well.

Is this with a stock cat or a 'high-flo' performance cat ?
The stock O2 sensors & PCM don't work well with those high-flo performance cats.

If it is your stock cat going bad; TAKE IT TO A GM DEALER !
You have an emission warrenty from GM on the cat for like 8-years or 130K km / 80.7K miles.
If they change the cat; you will get another set of O2 sensors & down-pipe (according to others who have had it done under GM warranty)


Note: Bank 1 & 2 does not apply to our cars with only 1 cat/exhaust system; if we had an V8 engine with true dual exhaust & dual cats, there is where bank 1 & 2 would come into play.

mmaxwell
06-06-2004, 06:18 AM
I have a stock cat. and exhaust. When I had the code checked it was cleared and hasn't come back on yet. Do I have to wait for it to come back on or can the dealership check with a sniffer or something like that?