is it just the o2 sensor ? my car is a 2000 and has 59k on it. with a hooker catback with a cut out. and a lid. and i hear a weird rattle very light but its there.

 

bump ttt

 

http://www.ls2.com/boggs/dtcs/DTC%20P0420.htm

 

I had that code, it ended up being a bad cat <drivers side> I believe......was a while ago so don't quote me on that....

 

yea i think it is ill see this weekend i have other stock cats so its not a big deal.

when you changed the cat was it tuff? any tips for me?

 

Lots and lots of PB blaster, let it sit overnight. Also wouldn't hurt to pick up two of the screw in studs for the cat unless the new one comes with it, the old ones don't seem to want to come off in most cases. Oh, and go buy a new gasket, you'll probably need it <not cheap BTW>

 

The P0420 usually ends up being the cats. To check this tap the cats with a rubber mallet to see if u can hear if its broken up inside.

 

oh i hate that.....happened to my 6 cyl. but mine got crushed which evidently breaks up the crap inside...it also dropped my gas milage by like 5mpg

 

Happened to me, car started running really bad, then i got the code...pinging, bad gas mileage, i think the price of a new cat is something ridiculous. Perfect time to buy some headers!

 

You can get your cat replaced for free under warranty. Just take it to the dealership and they will replace it for free.

See this thread: https://ls1tech.com/forums/pcm-diagnostics-tuning/418571-p0420-catalyst-system-efficiency-below-threshold-bank-1-a.html

 

Will they still honor this warranty if your not the original owner of the vehicle?