P0420 OBD II Trouble Code Code: Catalyst System Efficiency Below Threshold (Bank 1)

How to diagnose, repair, and info on symptoms and causes of a P0420 OBD-II trouble code which means the catalytic converter is no longer performing at a normal level. Often this means the bank 1 converter will need to be replaced.

Symptoms of P0420 OBD II Trouble Code

Common Causes of P0420 OBD II Trouble Code