U0105 — Lost Communication with Fuel Injector Control Module

Causes

• Open or short in CAN bus wiring (CAN‑H or CAN‑L)
• Corroded, damaged or loose connectors at the FICM or gateway module
• Blown fuse or faulty relay supplying power to the FICM
• Missing or poor ground at the FICM or related control modules
• Low battery voltage or intermittent supply voltage
• Faulty FICM (internal failure)

Symptoms

• MIL/Check Engine lamp illuminated
• Scanner shows U0105 and module is missing/unavailable in network list
• Engine may crank but not start or run poorly
• Loss of sequential injector control, misfires or reduced power
• Other networked modules reporting communication faults
• Intermittent or permanent no‑start condition

What to check

• Read and record all stored and pending codes from all control modules
• Check battery voltage (with key on and cranking) and battery connections
• Inspect fuses and relays for the FICM and associated power circuits
• Visually inspect connectors and wiring to the FICM for damage, corrosion or water ingress
• Verify presence of the FICM on the scan tool network list
• Check for recent work or aftermarket installations that could affect wiring

Signal parameters

• CAN idle (recessive) voltage: ~2.5 V on both CAN‑H and CAN‑L
• CAN dominant state typical: CAN‑H ~3.5 V, CAN‑L ~1.5 V during active bits
• Termination resistance (across CAN‑H to CAN‑L): ~60 Ω (two 120 Ω terminators in parallel)
• Expected data rates vary by vehicle: commonly 250 kbps or 500 kbps (verify factory spec)

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