Emissions Code P0420

[Maxbaby]

Over the last 8 or 9 months I've thrown a P0420 emissions code every month or two. I reset it with my scantool and I'm good for another month or two. I've noticed a couple times it seems to happen when I've been in slow moving rush hour traffic. The truck has 98,000 km and runs great overall. Anyone have any suggestions?

[twavor]

Replace your catalytic convertor. You may want to check out your O2 sensor for that particular convertor first, but everytime I've had that code, it meant replace the convertor and you'll be fine. The convertor is not doing it's job and that's usually what sets that code.

 

Travis

[Jfriday]

It's been showing up on my '07 GMT 900 here lately as well. The truck has less than 70,000 miles on it, only 70k out of a cat really kinda pisses me off.

[redvett]

Its still under emissions warranty get it fixed.

 

It's been showing up on my '07 GMT 900 here lately as well. The truck has less than 70,000 miles on it, only 70k out of a cat really kinda pisses me off.

[Maxbaby]

Hey guys, thanks for your fast replies. I agree with JFriday, not a lot of mileage for a cat, but I suppose it's better than an entire exhaust. Not having worked on such a thing, is it fairly DIY friendly (is there a how-to with pics that someone knows of)? Should I just be replacing the 02 sensor anyway (how would I tell if it's good or bad?) And any recommendations on what kind to buy?

[twavor]

If it's under warranty let your local GM dealership tackle it...you'll get both replaced there more than likely . If it's not under warranty, I'd still definitely take it to a good exhaust shop...some of them will still tell you to take it to the dealer, but some will do it. The ones I've sent to the exhaust shop were $250 +/-. Like I said earlier...it's not plugging up, it's not doing it's job...basically flowing too freely.

 

Travis

[Maxbaby]

I was looking online at a few parts stores and saw this as an example...

http://www.partstrain.com/store/details/Ch.../EAST50366.html

This looks like a bolt on DIY system... is that what I should be looking at?

[twavor]

I was looking online at a few parts stores and saw this as an example...

http://www.partstrain.com/store/details/Ch.../EAST50366.html

This looks like a bolt on DIY system... is that what I should be looking at?

Looks good to me, that's not a bad price.

Before you get the cart ahead of the horse, you may want to make sure you just haven't got an O2 sensor reading wrong or some other problem. Gets kind of expensive throwing parts at the problem before checking it out thoroughly.

 

Travis

[Maxbaby]

I eyeballed the wiring to both sensors and they appear to be intact. How do I test to see if it's a sensor?