P0640 OBD II Trouble Code Intake Air Heater Control Circuit

How to easily diagnose, repair, and info on causes of a P0640 trouble code that indicates a detected failure of the intake air heater control circuit.

Symptoms of P0640 OBD II Trouble Code

  • Diminished fuel efficiency
  • Rough idle on cold start
  • Drivability issues when cold
  • Other IAT codes

Common Causes of P0640 OBD II Trouble Code

  • Defective or disconnected intake air temperature sensor
  • Faulty intake air heater relay or fuse
  • Shorted or open wiring or connectors
  • Burnt out intake air heater element
  • Bad PCM or programming error

Severity of P0640 OBD II Trouble Code

Intake air temperature codes should be classified as severe and addressed as such. A code P0640 may be accompanied by various drivability symptoms, especially when the engine is cold.