I have a 2005 Cadillac CTS 3.6l V6. And my check engine light is giving me P0420 and P0430 codes. I don't know whether to replace the catalytic converters or change the 02 sensors.
How long have you had the new cats?It is better to get your direct fit catalytic converters from rockauto.com. I had both codes and have felt a real difference with the ride. Haven't had any issues yet.