Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
how did you test the cat?
have you performed a back pressure test?
was it a new aftermarket? new oe? direct fit? weld in? universal? and no not with a potatoe with a gauge threaded into the upstream 02 hole that measures converter flow
does it run good do you just want to eliminate the light? you can run cheaters and likely get rid of the po420... aftermarket conerters can be a night mare.. they do no always flow like a factory.. napa sells walker exhaust and its a roll of the dice if it will work
here is he gauge I refer to http://www.zoro.com/westward-tester-exhaust-pressure-1mzt5/i/G1218725/?gclid=CjwKEAiA8qG1BRDz0tmK0pufw3QSJACfn6ol6Xxuuq_N3a56WttvWyCCU7VSScwdDvVMKD-aoDfrAxoCAR7w_wcB&gclsrc=aw.ds