The P0420 trouble code suggests that the catalytic converter on Bank 1 of your 2001 Chevy Impala is not functioning properly. Here are some possible causes for this code:
- Faulty oxygen sensor(s)
- Damaged catalytic converter
- Exhaust leak
- Faulty engine control module (ECM)
To diagnose and fix the issue, it's recommended to seek professional assistance from a qualified mechanic. They can perform proper diagnostics and replace any faulty components as needed.
