Throwing code PO420

**locrian** · 02-07-2007, 12:40 PM

what is it? car runs great. guy at autozone said it could be a bad cat, or an oil seal leak causeing the cat to proform below par. 2000 Z28.

**ice97ta** · 02-07-2007, 01:45 PM

wrong section, should be in one of the maintenance sections

**jbb6811** · 02-07-2007, 01:49 PM

take it to your dealer ship. i got a 00 z28 and got a letter stating they(cats) could be from a bad batch and they could be replaced free. look into it!

**2001NBMZ28** · 02-07-2007, 01:51 PM

Think you posted in the wrong section, although P0420 usually means the drivers side cat is bad and killed itself.

If you're stock you can swap the rear 02's from side to side and see if the code changes to P0430 for the other side - but it's probably the cat. Just to be sure you know, stock cats are now covered under warranty for 120K miles on the '00-'02 cars.

**pocheasy** · 02-08-2007, 08:37 AM

I was reading an article in the paper yesterday saying how much used cat's are fetching these days for the metal. $75-$150 is what places are paying for them used. around here I guess theres ben people going around stealing them off cars

**locrian** · 02-08-2007, 08:43 AM

let me check...IT'S GONE!!!!

j/k...

**2manycis** · 02-11-2007, 11:52 AM

check the temp b4 and after the cat while the car is hot and running. If the temp is way cooler (like 200 degrees), then you have a bad cat. If not then It could be an exhaust leak, which could easily be heard... and if that's all good, then it's time to replace an 02 sensor.

**bevenue** · 02-11-2007, 05:11 PM

Originally Posted by 2001NBMZ28

Just to be sure you know, stock cats are now covered under warranty for 120K miles on the '00-'02 cars.

I say the drivers side cat.

TomSS · 03-11-2007, 06:23 PM

The code 0420 is the same for 96 ImpalaSS w/LT1. Drivers side cat. 0430 is the passenger side. Finally had to have both of my cats removed. Due to being an old engine and the occasionaly blue smoke, I don't want to install new cats until the engine ahead blowing clean exhaust. I was able to come up with a couple of simulators and clear the codes. I could clear my codes but the CEL would come back in one driving cycle. I pass this along because I'm thinking of an LS1 for an LT1. What I've read about the LS1, I like.

TomSS