CAN network

U0105 — Lost Communication with Fuel Injector Control Module

Severity: high Drive with care, to a shop

What U0105 means

U0105 means a control unit stopped receiving messages from the fuel injector control module over the CAN network. On diesels and some multi-ECU gasoline vehicles, this module drives the injectors and sets injection timing and duration. Without communication, the engine cannot meter fuel accurately.

Symptoms

  • No-start or limp mode
  • Check Engine light on
  • Other U-codes stored at the same time
  • Rough running, possible misfire
  • Possible increased fuel consumption
  • Loss of power under load

Possible causes

  1. Failed injector driver module
  2. Damaged, shorted or corroded CAN wiring in the engine bay
  3. Low system voltage or a weak battery
  4. Blown fuse feeding the module
  5. Poor connector contact or missing module ground
  6. Moisture or oil intrusion in the connector or module
  7. Faulty injectors overloading the driver

How to diagnose

  1. Scan all modules and note which ones aren't responding, and review the freeze frame data
  2. Test battery voltage and charging voltage, and inspect the terminals
  3. Check the fuses and relays that power the injector module
  4. Inspect the module, connectors and harness for moisture, corrosion and chafing
  5. Check power and ground at the module connector with a multimeter
  6. Test the CAN-H and CAN-L wires: about 60 ohms between them with the ignition off, and continuity of each wire
  7. Check injector circuits and resistance, and compare cylinder balance
  8. If equipment allows, check module communication and look for software updates

Common fixes

  • Charge or replace the battery and clean the terminals and ground points
  • Replace the blown fuse after finding what overloaded it
  • Repair the harness or CAN wiring and replace damaged connectors
  • Replace faulty injectors that have damaged the driver
  • Replace or reflash the injector control module and code it to the vehicle

Questions and answers

Can I drive with a U0105 code?

It's best not to. If the engine runs, drive only a short distance to a shop, since it may stall or lose power. If it won't start, arrange a tow.

What most often causes U0105?

Power and network problems are most common: a weak battery, a corroded connector, a poor ground or damaged CAN wiring. The module itself fails less often, so check power and wiring first.

Will U0105 go away if I clear it?

You can clear it, but it will return if the cause is still there. Clear it only after repairs, and confirm that communication with the module is restored.

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.