U0109
System
Network (CAN Bus)
Scanner required
Full-system scanner (engine, ABS, SRS, transmission, service resets)

Lost Communication with Fuel Pump Control Module

Understand U0109, common causes, and the right TOPDON scanner to diagnose it.

Fuel pump control module not on network — fuel delivery may be affected.

Common symptoms

  • No-start
  • Engine stall
  • Fuel pump silent

Typical causes

  • Failed fuel pump module
  • CAN wiring
  • In-tank module connector corrosion

What scanner do you need?

Full-system scanner (engine, ABS, SRS, transmission, service resets)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

Can I diagnose U0109 with a basic code reader?
U0109 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Is it safe to drive with U0109?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.