TorqueMech OBD Code Guide
U0140 - Lost Communication With BCM
Communication lost with body control module.
Code first. Confirm symptoms and checks before pricing parts.
Read code pattern
Check likely system
Estimate after confirmation
Common Next Steps
Turn the code into the next check.
Test charging voltage
Measure alternator output and battery voltage under load.
Inspect serpentine belt
Check belt condition, tensioner travel, and pulley alignment.
Verify battery condition
Charge and load test before blaming the alternator or starter.
Related Inspection
Code Overview
Communication lost with body control module.
Common Causes
- Low system voltage
- CAN wiring issue
- BCM power/ground issue
Diagnostic Steps
- Check battery/charging
- Check BCM fuses/grounds
- Inspect CAN wiring/connectors
Related OBD Codes
Browse nearby codes when systems overlap.
Next Steps
Move from code to checks, then estimate.