Hey guys, I'm looking for a little guidance here. I'm getting the error P0420, which is the "catalytic converter code". The reason I'm a little confused is that even though I'm getting that code, my truck's emissions are perfectly fine, as a matter of fact nowhere near any of the limits for the required smog test. I of course failed though because of the error code. I just replaced all of the oxygen sensors, cleaned out the fuel/exhaust system, and had the code reset. It's now 4 days later, and the light just popped back on with the same code. If the problem were really my converter, wouldn't my truck fail emissions? Is there any other part besides the oxygen sensors or converter that may be bad? Thanks for your help.

 

The catalytic converter might have the honeycomb material cracked or broken. Have you noticed any loss of power?

 

Look HERE, maybe it'll help?

 

I forgot if our trucks have a downstream O2 sensor after the cats..if so, that sensor could be malfunctioning. that would cause that code as well.

 

your truck is 420 friendly

 

Also check for exhaust leaks at the gaskets behind the manifolds.