16804/P0420/001056

From Ross-Tech Wiki

16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold

Possible Causes

  • Leakage in Intake and/or Exhaust System
  • Catalyst faulty
  • Oxygen Sensor(s) faulty
  • Oxygen Sensor(s) Control faulty

Possible Solutions

  • Check Intake and Exhaust System for Leaks
  • Check Catalyst
  • Check Oxygen Sensor(s)
  • Check Oxygen Sensor(s) Control
    • Perform Oxygen Sensor(s) Aging Check

Special Notes