CAN network

U0119 — Lost Communication with Fuel Rail Valve Control Module

Severity: medium Drive with care, to a shop

What U0119 means

U0119 means the engine computer or another module on the CAN bus has stopped receiving messages from the module that controls fuel rail pressure. This module normally drives the pressure regulating valve or actuator and reports its status over the network. Without that communication, fuel pressure control becomes unreliable and the engine may enter limp mode.

Symptoms

  • Hard starting or extended cranking
  • Limp mode and reduced power
  • Related fuel pressure codes
  • Several warning lights on at once
  • Functions of the affected module unavailable
  • Possible engine stalling

Possible causes

  1. CAN bus wiring fault (open, short or chafed harness)
  2. Corroded connectors or terminals at the module
  3. Low battery or system voltage
  4. Power supply or ground fault at the module
  5. Failed fuel rail valve control module or pressure actuator driver
  6. Another faulty module loading down the bus

How to diagnose

  1. Run a full-module scan to see which modules are not communicating
  2. Test battery voltage and charging system output
  3. Inspect the module's wiring and connectors for damage, moisture and corrosion
  4. Check the module's power and ground circuits against the wiring diagram
  5. Measure CAN bus resistance and CAN-H/CAN-L voltages at the diagnostic connector
  6. Disconnect suspect modules one at a time, only following a documented procedure
  7. Clear the code and see whether it returns

Common fixes

  • Repair or replace damaged wiring and terminals
  • Clean connectors and restore good grounds
  • Charge or replace the battery and fix any charging problem
  • Replace the faulty fuel rail valve control module and program it as required
  • Replace any module that is disrupting the bus

Questions and answers

What does U0119 mean?

It means communication has been lost with the fuel rail valve control module. Other modules on the CAN bus can't get data from it, so fuel pressure control may not work correctly.

Can I drive with code U0119?

Only carefully and for a short distance. There is a risk of power loss or stalling, especially in traffic or at highway speed.

Where do I start diagnosing U0119?

Check battery voltage first, then the module's power, ground and connectors. After that, inspect the CAN wiring and test the bus with a multimeter or scope.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.