› Forums › Car Problems & Maintenance › Chevrolet › Why does my 2003 Silverado show P0420 & P0430 codes?
May 14, 2025 at 7:28 pm
#1456
Jim
Sounds like it needs cats. Bank 1 (420) & Bank 2 (430). When you erase the codes, it takes a bit of driving for the PCM to fail them again. If it’s a ¾ton you may not need emissions, which wouldn’t matter if your CEL is on.