P0633 OBD II Trouble Code Immobilizer Key Not Programmed ? ECM/PCM

How to easily diagnose, repair, and info on causes of a P0633 trouble code that indicates an immobilizer key that is not programmed.

Symptoms of P0633 OBD II Trouble Code

  • No start condition
  • Lock/unlock functions may be disabled
  • Vehicle security system may be activated
  • Other diagnostic codes will likely be stored

Common Causes of P0633 OBD II Trouble Code

  • Weak immobilizer key battery
  • Immobilizer key malfunction
  • Immobilizer key replaced without being programmed
  • ECM/PCM programming error
  • ECM/PCM swapped between vehicles and/or replaced without being properly programmed
  • ECM/PCM failure

Severity of P0633 OBD II Trouble Code

A stored code P0633 should be categorized as severe. If the controllers fail to recognize the immobilizer key, important functions (engine start-up and door unlocking) could potentially be disabled.