#Explanation #Symptoms #Causes #Troubleshooting

What does P0633 Immobilizer Key Not Programmed – ECM/PCM mean?

The P0633 code, also known as the Immobilizer Key Not Programmed – ECM/PCM code, is a common issue found in many OBD-II vehicles.

When this code is stored, it means that the engine control module (ECM) or powertrain control module (PCM) has detected an immobilizer key that it does not recognize.

The immobilizer key is a security feature used to prevent vehicle theft and eliminate the need for a physical key.

It emits a unique signal to the ECM/PCM and other controllers when in close proximity to the vehicle, allowing for functions like unlocking the doors and starting the engine.

If the ECM/PCM fails to recognize an immobilizer key, a P0633 code may be stored and a malfunction indicator lamp (MIL) may be illuminated.

This code should be taken seriously, as it can potentially disable important functions, such as engine start-up and door unlocking.

Possible causes of this code include a weak key battery, a malfunctioning key, a key replaced without programming, programming errors, or ECM/PCM failure.

It is important to address this code promptly, as it may require reprogramming of the ECM/PCM or key replacement.

P0633 Symptoms

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

Possible P0633 Causes

  • 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

Troubleshooting P0633 error code

  1. Connect a diagnostic scanner to the vehicle diagnostic port
  2. Check if the ECM/PCM is recognizing the immobilizer key
  3. If ECM/PCM is not recognizing any immobilizer key, check if the key fob battery is dead or an incorrect immobilizer key is being used
  4. If an inadvertent immobilizer key yes signal is displayed, suspect ECM/PCM replacement without proper programming
  5. Consider using reprogrammed, aftermarket, replacement controllers and immobilizer keys
  6. System reprogramming may be required if replacing any vehicle security system component or controller

See other p06 OBD Codes

OBD CodeOBD Name
P0608Control Module VSS Output A Malfunction
P0632Odometer Not Programmed – ECM/PCM
P0609Control Module VSS Output B Malfunction
P0630VIN Not Programmed or Incompatible – ECM/PCM
P0698Sensor Reference Voltage 'C' Circuit Low
P0631VIN Not Programmed or Incompatible – TCM
P061EInternal Control Module Brake Signal Performance
P0664Intake Manifold Tuning Valve Control Circuit Low Bank 2
P060CInternal Control Module Main Processor Performance
P067BCylinder #4 Glow Plug Circuit High

OBD Trouble Codes Ranges

b00 p00 p01 p02 p03 p04 p05 p06 p07 p08 p09 p0a p0c p10 p11 p13 p14 p16 p20 p21 p22 p23 p24 p25 p26 p27 p28 p2a p2b p34 u00 u01 u02 u10 u30