2000 Chevrolet Silverado 1500 P0420 Code: Cat Converter Failure or Exhaust Flow Issue?
Hello everyone, I have a 2000 Chevrolet Silverado 15-00 with a 5.3L V8 engine. I recently replaced all four oxygen (O2) sensors, and there are no exhaust leaks—my truck runs smoothly with no noticeable exhaust restriction. However, it still shows a P0420 fault code. The truck has accumulated 145,000 miles, which raises concerns about catalytic converter degradation. I've reset the codes and driven it for a day before returning to check—no improvement. I'm considering replacing the catalytic converters due to their age, but I'm worried about costs: y-pipe replacement can run up to $500. Is it possible to remove the existing cat converters, replace them with new ones, and then weld them back into place? Would that be a viable option instead of buying a full new y-pipe assembly? Any insights or experiences from owners of this model would be greatly appreciated.
The catalytic converter is likely worn out. By the time you factor in both the cost of new converters and the labor for welding and fabrication, the total expense may end up close to buying a full replacement y-pipe assembly.