Ive got a question my car is throwing a code and it comes up as p0420 wich is a ( catalyt system low effidiency bank 1 ) its a pending code and im constantly having to delete it, could it be due to the fact that i drive around with my cut-out open ? however the cutout is posistioned after the catalytic converter......... if anyone else knows what is causing this or can tell me how to fix it, ide sure appreciate it !

 

How many miles do you have on the cats? It may be a legit code. The longest I have seen one last is 260k miles, but I have seen them go bad in under 30k miles. It could also be an o2 sensor problem as well.

 

well it appears that you know how to test it, to find out if it is the cutouts causing it.

Cap your cutouts and see if the code doesn't come back.

Do you have an engine tune that would run you richer than stoich and would lower the effic of your cats faster

 

The car has 66k miles on it, and no the engine tune is all stock and has been for a few weeks.

 

Not the cutout if it's under the rear seat, mine's never thrown a code. Sometimes they just go bad, GM extended the cat warranty on the 00-02 cars to 10yrs/120K back in December.