P0420 - Por Que?

[ShadowGT]

Catalyst System Efficiency Below Threshold (Bank 1) Code P0420

What's this? I have to brand new O2 sensors up and down stream. Brand new PCV installed and this code has never come up for the last year until now. Both O2 sensors are Bosch with OEM harnesses.

No exhaust leaks that I know of. Car runs fine, gets 22 miles per gallon still and idles at 700RPM.

So what now? New Cats?

[green97gt]

sounds like you need a cat sir.

i had that code, replaces both o2s, ran thru everything else, all that was left is a cat. thats what i did... they can be found on ebay for pretty cheap(what i bought)..dont know how long they last...20k later my sisters is going fine....thats not saying much, but that what i know.

or you can try the spark plug non fouler trick. theres a link here on sli...cant find it, but someone will post...in my opinion, its no fix for bad cats, IMO soon they will become clogged.

[ShadowGT]

Hmm, thanks for the input.

I should look up a high flow cat. I got the UEL headers and the N1 muffler. Might as well go all the way.

[EyeOTheMastodon]

Code P0420 can mean only one thing! Needz moar Mr. Green!!

[Black_Adder]

I have been getting P0420 ever since installing the UEL headers as well. I came across this thread today:
http://www.sl-i.net/FORUM/viewtopic.php?f=39&t=14675&p=208483&hilit=p0420

I am definitely going to be trying this ASAP, I would say its worth a shot before investing in new cats!