reoccuring P0420 code

[skipfleming]

Hi I'm new here.. i was hoping that someone could help me,, I'm getting a reoccuring P0420(left bank Cat converter below efficiency) I have a 2002 Trans -Am WS-6 Automatic, with A K&N air filter,and a header back exhaust with High flow cats,, I've changed both of the left side O2 sensors but that only made it worse.. the Exhaust has the bung spacers for the O2 sensors. I've been told that it could be the MAF sensor.. or the TEMP sensor could be at fault,, does anyone have any suggestions,,P.S. I still runs like a striped ass ape even when the light come on .

[KahanaReef]

Welcome to the site! I've put a copy of your post in the general help section. You'll get more responses in there.

Since you have a 2002, it would be worth while to see when your car was put into service as it may meet the requirements for the extended warranty on the cats. When I started throwing that code, I had just missed the deadline by a few weeks

[wileyCoyote]

welcome hope you get if figured out!

[383ls6]

it needs a drivers side catalytic converter.