U0109
NetworkModule Communicationhigh severityLost Communication with Fuel Pump Control Module
What U0109 Means
Cannot communicate with the fuel pump control module that manages fuel pump speed and pressure.
Symptoms
- Engine stalling
- No start condition
- Low fuel pressure codes
- Fuel pump not running
- Extended crank time
Common Causes
- Fuel pump module failure
- CAN bus wiring damage
- Module power loss
- Fuse blown
- Fuel pump connector issue
Diagnostic Steps
- Check fuel pump module fuse
- Test module power and ground
- Check CAN wiring
- Test fuel pump operation directly
- Check fuel pump relay
Where to start: Check fuel pump relay and fuse first. Module mounted near fuel tank is prone to corrosion.
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