Incorrect Immobilizer Key
The PCM has detected an incorrect or invalid immobilizer key/fob, disabling engine start and fuel/ignition systems as a security measure. This prevents the vehicle from operating until the correct transponder key is used or the system is reprogrammed.
What You Might Notice
- Engine will not start
- Flashing security light in instrument cluster
- Service Engine Soon lamp illuminated
- Engine may start after delayed reset period
- No fuel pump activation
Most Common Causes
- 1
Defective immobilizer key or key fob
The transponder microchip in the key or fob is damaged, dead, or not communicating with the PCM's electromagnetic field reader.
- 2
PCM immobilizer programming mismatch
The vehicle's PCM has lost synchronization with the key code or was reprogrammed with incorrect key data, rejecting all key attempts.
- 3
Faulty PCM or immobilizer module
The PCM's transponder reader circuit or immobilizer module has failed, preventing it from recognizing any valid keys.
- 4
Corroded or damaged key contacts
Physical wear or corrosion on the key's transponder connections reduces or blocks signal transmission to the vehicle's receiver.
How to Diagnose It
- 1
Check Defective immobilizer key or key fob — The transponder microchip in the key or fob is damaged, dead, or not communicating with the PCM's electromagnetic field reader.
- 2
Check PCM immobilizer programming mismatch — The vehicle's PCM has lost synchronization with the key code or was reprogrammed with incorrect key data, rejecting all key attempts.
- 3
Check Faulty PCM or immobilizer module — The PCM's transponder reader circuit or immobilizer module has failed, preventing it from recognizing any valid keys.
- 4
Check Corroded or damaged key contacts — Physical wear or corrosion on the key's transponder connections reduces or blocks signal transmission to the vehicle's receiver.
How to Fix It
- 1
Replace immobilizer key or key fob
Obtain a new OEM transponder key programmed to your vehicle's VIN and have it coded by a dealer or locksmith with immobilizer programming equipment.
- 2
Reprogram existing key to PCM
Use a professional diagnostic scanner or dealer service to reprogram the PCM's key memory with your existing key's transponder code, clearing the mismatch.
- 3
Test and replace PCM if faulty
Have the PCM's immobilizer circuitry tested with specialized equipment; if defective, replace the PCM and reprogram all keys to the new unit.
- 4
Clean or replace key transponder contacts
If the key shows visible corrosion or damage, attempt to clean contacts with electronics cleaner; if unsuccessful, the key transponder assembly must be replaced.
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