After an ignition module failure, the cataytic converter needed replacement. I'm getting a P0326 and P0420 code. The dealer also claims that I need to have the PCM reprogrammed. Is that true, and what it that going to affect. The car runs fine.
catalytic converter replacement on 2005 Saturn Ion
There is a Saturn factory Technical Service Bulletin that describes reprogramming the PCM before replacing the Catalytic Converter.