P0420 & P0430: Catalyst Efficiency Codes
Jan 28 2020
5 mins
This TSB was released by General Motors, covering most of their large SUV’s and vans that have been produced from 2002 and up. The related DTCs that a technician may find are P0420, Catalyst Efficiency Below Threshold, and/or P0430, which is the same thing, Catalyst Efficiency Below Threshold, just for bank 2. Technicians are seeing these codes on low mileage vehicles, or vehicle