U0109 Lost communication with fuel pump control module
What U0109 means
Many cars control the fuel pump speed through a separate module, often located near the tank or in the boot. U0109 means other modules stopped receiving its messages. The pump may run at a fixed speed or stop, which can cause power loss, stalling or a no-start.
U0109 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 80–1500 €
- Workshop time
- 1–5 h
- Repair difficulty
- Hard
- DIY possible
- No
- Check engine light
- Yes
- Affects emissions test
- Yes
- Limp mode possible
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Hard starting or no-start
- Stalling or power loss
- Limp mode
Common causes
- Corroded fuel pump control module or connector (often from water ingress)
- Blown fuse or failed power supply
- Damaged CAN bus wiring
- Poor ground at the module
- Failed fuel pump control module
Can I keep driving with U0109?
You can drive if the engine runs normally, but have it checked within one or two weeks. The car may stall or fail to restart.
What to check first
- Check the fuel pump control module fuse and battery voltage
- Inspect the module and connector for water or corrosion
- Check power, ground and CAN wiring at the module
- Replace the module if it does not communicate
Related codes
- U0120 Lost communication with starter/generator control module
- U0121 Lost communication with ABS control module
- U0126 Lost communication with steering angle sensor module
- U0127 Lost communication with tyre pressure monitor module
- U0140 Lost communication with body control module
- U0184 Lost communication with radio
- U0046 Vehicle communication bus C fault
- U0252 Lost communication with rear lighting control module B
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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