I had 430 and 420 codes as well I cleaned the tb as well but with tb cleaner and didnt run the car at the time. however my codes returned...the stealership said it would cost $1600 to change the cats. Another shop told me they can cut it out and replace it without removing the manifolds. I have been trying to get a solution to my code problem for a while. Have you done anything special inorder to pass the emmissions?
