OBD-II trouble code
U0105: Lost Communication with Fuel Injector Control Module
A module on the network can no longer hear from the fuel injector control module. Usually a power, ground, or wiring fault — and because this module drives the injectors, the engine may misfire, run rough, lose power, or fail to start.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $100 – $1,200
- DIY difficulty
- Shop recommended
What does U0105 mean?
U0105 is set when another module on the vehicle's communication network — usually the engine computer — stops receiving messages from the fuel injector control module. On many high-pressure and diesel fuel systems, a dedicated module generates and switches the high-voltage or precisely-timed pulses the injectors need; it takes commands from the engine computer and reports injector status back over the network. When the network loses contact with that module, U0105 records the dropout.
The causes follow the familiar communication-code pattern. The fuel injector control module may have lost power or ground through a blown fuse, corroded ground, or failed relay. The CAN wiring or connector at the module can be damaged or corroded, often from engine-bay heat, vibration, or oil and coolant exposure. The module's internal communication circuitry can fail, or another module on the bus can disrupt communication for everyone. Low system voltage from a weak battery or charging fault can also cause intermittent dropouts.
Because injector operation depends on this module, the symptoms are usually significant. The engine may misfire, run rough, hesitate, lose power, or fail to start at all if injector control is lost across the board. The check engine light comes on, typically with companion misfire or injector-circuit codes. An engine that can't fuel its cylinders reliably is both a driveability and a safety concern — it may stall without warning — so U0105 warrants prompt diagnosis rather than continued driving.
Common causes
- Blown power or ground fuse for the fuel injector control module
- Corroded or loose ground at the module
- Damaged CAN wiring to the fuel injector control module
- Corroded or backed-out terminals at the module connector
- Engine-bay heat, vibration, or fluid exposure damaging wiring
- Failed internal communication circuitry in the module
- Another module on the bus disrupting network communication
- Low system voltage from a weak battery or charging fault
Symptoms
- Engine misfire, rough running, or noticeable power loss
- Hard starting or a no-start condition
- Engine stalls or hesitates under load
- Check engine light on, often with misfire or injector-circuit codes
- Scan tool can't communicate with the fuel injector control module specifically
- Symptoms may be intermittent with a marginal connection
- Other U-codes stored in modules that depend on injector data
Diagnostic steps
- 1.Scan all modules; confirm the fuel injector control module is the one that's unreachable while others respond.
- 2.Check the module's power and ground fuses and the relevant relays.
- 3.Inspect the module ground point and connector for corrosion, looseness, heat damage, and fluid intrusion.
- 4.Measure CAN-High and CAN-Low at the module connector (rest near 2.5 volts) and verify continuity back to the bus.
- 5.Test the battery and charging system, since low voltage can cause intermittent communication loss.
- 6.If power, ground, and wiring are good but the module still won't communicate, the module itself is the likely failure and will need replacement and programming.
Repair cost
$100 – $1,200
A blown fuse, corroded ground, or connector repair is the cheapest fix at $100-$300 once located. Wiring repair runs $200-$600. Diagnostic time commonly adds $150-$300. Fuel injector control module replacement is the most expensive outcome at $400-$1,200 including programming, and is a last resort after cheaper causes are ruled out. Costs rise on diesel applications where the module is integrated and harder to access.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with module communication / can bus diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.