P0422 OBD II Trouble Code Main Catalyst Efficiency Below Threshold (Bank 1)

Detailed information on troubleshooting and repairing a P0422 DTC code which has to do with the catalyst system. Also includes links to relevant forum topics on the code.

Symptoms of P0422 OBD II Trouble Code

  • Increased tailpipe emissions
  • MIL (Malfunction Indicator Lamp) illumination

Common Causes of P0422 OBD II Trouble Code

  • Bad or non-functional catalyst
  • Engine operating out of optimal air:fuel ratio