P0423 OBD II Trouble Code Heated Catalyst Efficiency Below Threshold Bank 1

Symptoms of P0423 OBD II Trouble Code

  • Decreased fuel efficiency
  • A lack of general engine performance
  • Other related diagnostic trouble codes
  • MIL (malfunction indicator lamp) illumination

Common Causes of P0423 OBD II Trouble Code

  • Bad catalytic converter
  • Ignition misfire/s
  • A faulty mass air flow or manifold air pressure sensor
  • Defective O2 sensor/s
  • Burnt, broken, or disconnected wiring and/or connectors
  • Pre-cat engine exhaust leak

Severity of P0423 OBD II Trouble Code

A stored code P0423 could indicate that the fuel delivery system is not functioning properly. It should be treated as severe.