This is a used ITR cat I assume. I just recently installed a Carsound high flow cat on my LS with no CEL. You never know what your gonna get when you buy used.
Originally Posted by Master Yodub
It's possible that the cat you got is bad...either clogged/poisoned, or the catalyst is loose. If you take the cat off, you should be able to see through it. If you shake it and it rattles, then the catalyst has broken loose and will not function.
werd