2005 Chevy Avanlanche running bad

Code PO 420 is a catalytic converter code. Any dealership code reader will also convert it to plain english for the mechanic that read the code. Whatever your warrently, all catalytic converters have a silent warrenty that the dealer is required to honor. They are playing dumb until your warrenty runs out. They know what this issue is. If they don't replace your catalytic converter call a lemon law lawyer.

what is the code, P0420?? if its the cat converter is bad why is the dealer clueless? how many miles?? converter has 8/80k warranty. if the converter is plugged up it will run bad, no power stall..... its the same as being constipated.