I have a friend who just bought a 2000 Camaro Z28, 65K miles. The SES light just came on and I went to Auto Zone to have the code read, this is what the print out says; Number Crosses: P0420 - The PCM has determined that the catalyst system efficiency for bank 1 is below threshold for the current operation conditions. (Bank 1 identifies the location of cylinder #1, while bank 2 identifies the cylinders on the opposite bank)

What does that all mean. Does that mean the O2 sensor is bad, or the cat? I have a set of O2 Simulators, would that fix it?

Also the main belt is making some noise, nothing too loud, but enough to get hear when the car is idling. Any ideas?

 

99 out of a 100 times it means the catalytic converter on that side has gone bad/weak, the good news is that the Federal govt. has required all manufatures since 1995 to warranty ALL cat. converters for 8 years 80K miles, I do ETing in Ga and I cant tell you how many peeps have failed on PO420 and the local dealer has had to replace the part even AFTER tring to FO'ver the owner I give the paper work that Ga. Clean Air Force provides ....and guess what ...they get a new converter Dont let the dealership pull any ****

 

Thats what I thought. Thank you for the P0420 help.

Can anyone help me with the squeeky belt? It seems to be in good condition, I've seen the stuff you can put on them that clain to stop that, is that okay to do? Is the water pump going bad?

 

Before you jump to the conclusion that it's the converter, jack up the car and swap the rear O2 sensors from side to side then wait for the code to pop up again. Get back to AutoZone and have it read again. If the code stays on the same side it's the converter, but if the code changes to the other side then it's the O2 sensor.

As far as the front rotational noise goes. Take the belt off and turn each item to see if they make any noises and turn smoothly. If anything is loose, rattles, oor squeaks then you've found the culprit. If everything is OK then put a new belt on and see how it is then. The car has 65000 miles on it a new belt is probably needed anyway.

 

Okay there are 4 O2 sensors. Are they the ones before the cat or after that needs to be changed. Auto Zone said it was the one before the cat that I needed to change. I have 02 Semulators for the back that I can put on, would that take the code away?

 

AZ is incorrect, P0420 and P0430 are post cat (rear) codes. 02 sims will work, but if it's the cat I'd get the free replacement.

 

Alright so its the drivers post O2 sensor. How do I know if its the cat or the O2 sensor? I don't want to go to the dealership and pay $85 for them to say its the O2 sensor. Is there anyway to tell for sure before I go to the dealership? I called a local dealership and asked what the P0420 meant and he "didn't have the P list codes" in front of him. Whats the best thing to do in this situation?

 

Yes, do what AL SS590 M6 suggested - swap the rear 02's from side to side, clear the codes. If P0420 comes up again it's the cat, if P0430 comes up for the passenger side it's the 02.

 

Alright I'll do that, thanks for all the help!

 

No problem - make sure you clear all codes after the swap. My money is on a bad cat.

 

the 02 pretty much has to be good to detect this code in the first place. $1,000,000 says its the cat.