U0109high severityNetwork
Lost Communication with Fuel Pump Control Module
on 2009 Audi Q7 4.2L V8 · AWD
What this code 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
Repair notes
Check fuel pump relay and fuse first. Module mounted near fuel tank is prone to corrosion.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
U0002
High Speed CAN Communication Bus Performance
U0003
High Speed CAN Communication Bus (+) Open
U0004
High Speed CAN Communication Bus (+) Low
U0005
High Speed CAN Communication Bus (+) High
U0006
High Speed CAN Communication Bus (-) Open
U0007
High Speed CAN Communication Bus (-) Low
U0008
High Speed CAN Communication Bus (-) High
U0009
High Speed CAN Communication Bus Shorted Together
U0010
Medium Speed CAN Communication Bus