› Forums › Car Problems & Maintenance › Chevrolet › Why does my 2003 Silverado show P0420 & P0430 codes?
May 14, 2025 at 7:28 pm
#1455
Kai
It needs CATS. Unless you’re in California, Colorado or one other state, I can’t remember they’re not ridiculous anymore.
If you don’t have the cash right now, and they unbolt, and they’re borderline, I know people can get them to work for another year or so by soaking them in detergent for a few days.
Sort of like shaking a toner cartridge.