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Home / DTC / U0256 — Lost communication with the front control interface module

U0256 — Lost communication with the front control interface module

Detailed page for trouble code U0256.

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U0256

LAND ROVER U — Network/User

Lost communication with the front control interface module

Brand: LAND ROVER
Type: U — Network/User
AI status
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ready
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Page language: EN

Causes

  • FCI module failure (internal electronics or firmware)
  • Power supply fault to the FCI (blown fuse, open feed, poor battery connection)
  • Poor ground at the FCI
  • Damaged connector or wiring to the FCI (open, short to battery, short to ground)
  • CAN bus physical fault (short between CAN H/L, short to ground or battery, open circuit)
  • Missing or incorrect bus termination (open/failed 120 Ω termination resistors)

Symptoms

  • One or more front-end electrical functions inoperative (lighting, door/lock inputs, front sensors or switches depending on vehicle)
  • Warning or malfunction indicator lamp(s) illuminated and stored U0256 in memory
  • Loss of remote/vehicle convenience functions (intermittent or permanent)
  • Other modules reporting network errors or additional U0xxx communication codes
  • Functions may work intermittently or only after key cycles

What to check

  • Read and record all stored DTCs and freeze frame data from all control modules with a capable scan tool
  • Check for related U‑codes in other modules to identify which bus is affected
  • Visually inspect FCI connector and wiring for corrosion, damage, pin backout, or moisture
  • Check engine/vehicle battery voltage and ground quality (voltage drops under load)
  • Check fuses and power feeds for the FCI circuit
  • Inspect CAN bus wiring and connectors along harness runs for chafe, exposed conductors, or repairs

Signal parameters

  • CAN recessive voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (no active dominant)
  • CAN dominant voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (typical differential ≈ 2 V)
  • Idle bus resistance: ≈60 Ω measured across CAN_H and CAN_L (two 120 Ω terminators in parallel)
  • Check for no-load shorts: CAN_H or CAN_L should not be shorted to chassis ground or battery (should read open/high resistance)
  • Key on, engine off: module supply voltages typically battery voltage (check service manual for exact pin voltages)

Diagnostic algorithm

  1. Connect a factory-level or OEM-capable scan tool. Read and save all U-codes and related module communication statuses. Note which control modules are non-responsive.
  2. Confirm whether the FCI module appears on the vehicle network (module list). If it does not respond, continue with bus and power checks.
  3. Perform a visual inspection of the FCI connector and wiring harness for corrosion, water ingress, pin damage, or repairs. Repair any obvious harness damage.
  4. Verify battery voltage (12.4–12.8 V nominal at rest) and check for voltage drops during key on. Check and replace blown fuses feeding the FCI.
  5. Verify ground integrity: measure voltage drop between FCI ground and chassis while operating circuits (should be very low,
  6. With key on, backprobe the FCI power pin(s) for B+ and the ground pin for good connection. Replace wiring or connectors if feeds are out of specification.
  7. Check CAN bus health: with ignition on, measure CAN_H and CAN_L voltages at the FCI connector. Confirm recessive/dominant behavior with bus activity. Measure resistance across H-L (~60 Ω).
  8. If a short to ground or battery is found on CAN lines, isolate sections of the bus by disconnecting other modules to locate the shorted/failed node.
  9. If bus and power/ground are good but module still non-responsive, check for software/calibration issues or module registration with gateway; consult Land Rover service information for reprogramming or module initialization procedures.
  10. If module is determined faulty after verifying power, ground, and bus, replace the FCI with an OEM part, program/configure per manufacturer procedure, clear codes and retest for proper communication and function.

Likely causes

  • Blown/loose fuse or poor B+ feed to the FCI
  • Corroded or disconnected ground at the FCI
  • Damaged CAN H/L wires or connector pins (physical harness damage at door, bulkhead or near front end)
  • Failed FCI module
  • Faulty termination on CAN bus or a shorted node causing bus failure

Fault status

⚠️ Status
Lost communication with Front Control Interface (FCI) module — FCI not responding on vehicle network. Check power/ground, CAN bus wiring/termination, and module presence.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

U0100 U0121 U0140 U0155 U0240
413

Browse 413 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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