AsEpSiS

iTrader: (11)

Service engine soon light came on just recently and has stayed on.....I wasn't beatin the car down, or anything...... just drivin down the highway. I had a tech at AutoZone run the tester for me. It ran a code 420. When I asked the dude what it meant, he said, "he had no idea". He looked it up in their little book and came up with a few scenarios...1.catalytic converter failure 2.Major exhaust leek 3.engine predetonation.
How would I tell which of these is wrong? the car runs great, I never smell ehaust, but I'm not sure how to test my cats? NE suggestions? Or do you think I should just take it to the Pontiac dealer n have them check it out!?

2001NBMZ28

P0420 is a drivers side cat inefficiency code - usually means cat is bad. GM just extended the warranty on them to 10yrs/120K on the 00-02 cars. If the code keeps coming back I'd leave it stored and contact a dealer for free replacement.

SStheBest

iTrader: (2)

time for mods!!!

KrazyDan

Long tubes and high flow cats? Gearchatter.com scroll down, youll get what your code means

Keego_Ridah

How many miles does the car have on the clock?

AsEpSiS

iTrader: (11)

Thanks for the replies gents! I have a 98 t/a w/just over 100k miles.....I just bought it off of some dude on Ebay about 3weeks ago. I don't know anything about the cars history "except from carfax". By looking at the car, I see and HEAR that it has headers and I'd say 3" (oval) exhaust and a cold air intake.
I drove it from KY to WI with no problems "service engine soon". Just all of a sudden the light came on this week while I was goin down the highway. The car still runs great!!

Intense

iTrader: (8)

Replace it if you wish. Depends on what mods and what state you live in.

smg267

iTrader: (23)

just have the code turned off. If you find a local speed shop they can prob do it for a fair price. If you are running an ORY pipe or even high flow cats, Correct me if I'm wrong, but even the high flow cats throw codes sometimes. As long as it's one of the rear 02 sensors it's not important. I forget the code my car was throwing but it was the passanger front 02 sensor. If your gas mileage is between 14-16mpg. It's def your front 02 sensor get it fixed ASAP!

Desert Rat

iTrader: (1)

detonation is something you can hear under load. Sounds like a clattering inside the engine. A common cause for that is insufficient octane in your gas.