Lost Communication with Fuel Injector Control Module
The U0105 code indicates that the vehicle's main control module (typically the ECM/PCM) has lost communication over the CAN bus with the Fuel Injector Control Module (FICM). The FICM manages injector operation in diesel engines, controlling injection pressure, timing, and duration. This loss of communication can stem from CAN bus wiring faults, power or ground issues at the FICM, or internal failure of the FICM itself. According to SAE J2012, 'U' codes denote network communication problems between modules.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Open or short circuit in the CAN bus wiring (short to ground or battery)
- Corroded, loose, or damaged connectors at the FICM
- Internal failure of the Fuel Injector Control Module (FICM)
- Power or ground supply problem to the FICM
- Fault in the ECM/PCM preventing communication
- Abnormal resistance in the CAN bus lines
3. Symptoms You Will Notice
- Engine may crank but not start
- Check Engine Light illuminated
- Rough running or misfiring
- Reduced engine power or limp mode
- No communication with FICM during scan tool diagnosis
4. Step-by-Step Diagnosis
Verify battery voltage and ground connections at the FICM
Inspect CAN bus wiring and connectors for damage, corrosion, or loose pins
Measure resistance and voltage on the CAN bus lines (CAN High and CAN Low) at the FICM connector
Check for communication with other modules to isolate the fault
If wiring and power are OK, suspect a failed FICM or ECM/PCM
5. Frequently Asked Questions
Is it safe to drive?▼
No, driving with this code is not recommended. The vehicle may stall, fail to start, or enter limp mode, posing a safety risk.
How much does it cost to fix?▼
Repair costs vary widely: from $100-$300 for wiring repairs to $800-$1,500+ for FICM replacement, plus diagnostic fees.