Lost Communication With Vehicle Immobilizer Control Module
What does U0116 mean?
The U0116 code means the vehicle's onboard diagnostic system has detected: Lost Communication With Vehicle Immobilizer Control Module. This is a critical severity code.
Common Symptoms
- Vehicle will not start -- security light flashing
- Immobilizer or anti-theft warning light on
- Key not recognized by the vehicle
- No crank or crank but no start condition
- Security system alarm activating randomly
Probable Causes (Ranked by Likelihood)
- Failed immobilizer control module Very High
- Damaged CAN bus wiring to immobilizer module High
- Faulty key transponder or key fob battery Moderate
- Immobilizer antenna ring failure Moderate
- PCM to immobilizer module sync lost Low
Step-by-Step Diagnostic Procedure
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Attempt to start the vehicle with a known-good key or spare key
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Scan for DTCs in the immobilizer and body control modules
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Check power and ground supply to the immobilizer module
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Verify CAN bus communication at the immobilizer module connector
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Inspect the immobilizer antenna ring around the ignition lock cylinder
Frequently Asked Questions
Can I drive with code U0116?
No. If the immobilizer module cannot communicate with the PCM, the vehicle will not start. The security system prevents engine operation when it cannot verify the key.
What causes U0116?
The most common cause is a failed immobilizer module. Wiring damage, a faulty key transponder, or a failed antenna ring can also cause this code.
Can I fix U0116 myself?
This is very difficult to fix yourself because the immobilizer system requires dealer-level programming tools to match the module, key, and PCM. A locksmith with automotive programming equipment may also be able to help.