Lost Communication With Fuel Pump Control Module A
What it means
U0109 means the ECM has lost communication with the fuel pump control module — the controller that manages fuel pump operation and pressure. Without it the engine can lose fuel delivery, leading to hard starting, stalling, or a no-start. It is usually caused by a wiring or connector fault, a lost power or ground feed, or a failed module rather than the pump itself. Because it can leave you stranded, treat it as a priority repair.
Can I keep driving? Risky — if the fuel pump control module goes silent the engine can lose fuel delivery and stall or fail to start, so treat it as a possible no-start and repair promptly.
Common symptoms
What you'll notice
- Hard starting, extended cranking, or no-start
- Engine stalling or cutting out while driving
- Check-engine light on, sometimes with fuel-related codes
- Fuel pump not priming when the key is turned on
Common causes
Most likely first
- Blown fuse or lost power/ground feed to the fuel pump control moduleLikely
- Damaged, corroded, or disconnected wiring or connector at the moduleCommon
- Failed fuel pump control moduleCommon
- CAN bus wiring fault between the module and the ECM/gatewayLess often
- Water intrusion or corrosion at the module, often mounted near the tankLess often
How to diagnose & fix
Work through it in order
- Scan for companion codes and check whether the module responds at all to a scan tool.
- Confirm power and ground at the fuel pump control module and check its fuse.
- Inspect the module's connector and CAN wiring for corrosion, damage, or water intrusion.
- Check the bus circuits between the module and the ECM/gateway for opens or shorts.
- If power, ground, and wiring are good but the module stays silent, replace it, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0109?+
Can I just clear U0109?+
Related codes
Often seen with U0109
Read & clear U0109 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.