GMC mechanic in DC area
 

Dear all,

I own a 2001 Chevrolet Camaro (V6 so it's not a real Camaro) that has had emission problems off and on for the past few years. I've replaced the O2 sensors and the catalytic converter. The cat was later replaced under warranty, but it has since failed. I can't pass inspection in DC until I can get the check engine light to stop showing. There is something that is causing the cat to fail, but I've been told it could be a variety of things.

The code I get is P0420 OBD-II. I was wondering if there is a mechanic that has experience dealing with GMC emissions in the DC area.

Thanks