P0633 Immobilizer Key Not Programmed ECM/PCM

Definition: The P0633 code indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected that the immobilizer key is not programmed. This can prevent the vehicle from starting as it fails to recognize the key.

p0633 – Immobilizer Key Not Programmed ECM/PCM

Typical Severity: Moderate

Common Causes

P0633 – Immobilizer Key Not Programmed ECM/PCM

Common Causes:

• Incorrect key programming
• Defective immobilizer system
• Faulty ECM/PCM
• Issues with the ignition switch

 

Common Misdiagnosis

OBD2 Code: P0633

Description: Immobilizer Key Not Programmed – ECM/PCM

Common Misdiagnosis: Replacing the ECM/PCM without checking if the key is correctly programmed or assuming a faulty immobilizer system when the issue may be due to a simple programming error.

 

Common Diagnostic Steps

OBD2 Code: P0633

Description: Immobilizer Key Not Programmed – ECM/PCM

• Verify the vehicle’s battery is fully charged.
• Check for any additional codes that may be present and address them first.
• Inspect the key for damage or wear; try using a spare key if available.
• Ensure the immobilizer system antenna ring around the ignition switch is not damaged or disconnected.
• Use a scan tool to check for communication between the ECM/PCM and immobilizer system.
• If no communication, inspect wiring and connectors between ECM/PCM and immobilizer system for damage or corrosion.
• If communication is established, attempt to reprogram the key using an appropriate diagnostic tool as per manufacturer instructions.
• If reprogramming fails, consider replacing the key or immobilizer module as necessary.