2003 Chevrolet S10 Q&A
2003 Chevrolet S10 Question: I just replaced Cat Converter then I got OBD code P0420. Are they related?
did you use a dealer cat or aftermarket?? the aftermarkets are cheaper but dont have enough precious metals to keep the light out. the dealer is more money but well worth it. Roy - mastertech6371
Make sure you have the P0300 issue fixed, what ever caused the misfire most likely caused the cat. converter to fail. The O2 sensor before and after the cat measure it's efficiency a bad sensor could inaccurately flag a cat code (P0420). Professional grade scan tool live data helps figure out troublesome codes but only as good as the person interrogating the data. - patrick mannion