U0140: Lost Communication with Body Control Module
Standardized SAE J2012 code · U01xx — Lost communication with modules
What does U0140 mean?
CAN messages from the body control module (BCM) are missing. Effects depend on what the BCM controls — typically interior lights, wipers, central locking, immobiliser handshake. On some cars the engine refuses to start because the immobiliser handshake fails.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
- High BCM unpowered
- Medium Water ingress into BCM (often footwell-mounted)
- Low Gateway module routing CAN messages incorrectly
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of U0140 on the same make and model first.
U0140 in the community
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