Code
U1401
HYUNDAI
U — Network/User
MOST Critical Unlock Detected
Views:
UK: 29
EN: 37
RU: 38
AI status
Completed
Completed
100%
Causes
- MOST optical ring or wiring damaged (broken/bent fiber, damaged connector)
- Faulty MOST transceiver/module (head unit, amplifier, gateway, camera module)
- Intermittent power/ground to MOST devices or low battery voltage during operation
- Incorrect or interrupted software update/firmware flash on a MOST device
- Unauthorized or unexpected module programming or configuration change
- Corrosion, loose connectors or water ingress at MOST components
Symptoms
- Audio, navigation or camera modules fail to initialize or lose audio/video
- Infotainment warning or network error messages displayed
- Certain multimedia functions intermittent or non-functional (radio, phone, media playback)
- Modules show as "locked", "unauthorized" or not present in diagnostic tool
- Possible loss of features that rely on MOST (amplifier, rear entertainment, camera feeds)
What to check
- Retrieve and record all stored network-related U-codes and freeze frame data with a capable scan tool
- Check vehicle battery voltage and charging system; note voltage during fault occurrence
- Visually inspect MOST fiber optic cables and connectors for damage, kinks, contamination or corrosion
- Verify power and ground at major MOST modules (head unit, amplifier, telematics/gateway) and associated fuses/relays
- Confirm recent service history for software updates or module replacements that could alter node authorization
- Use a dealer-level or MOST-capable diagnostic tool to read MOST node status, error counters and ring topology
Signal parameters
- MOST node ID/serial number status
- MOST link up/down and ring continuity status
- Error counter (CRC/bit error) on MOST ring
- Authorization/lock state bits for MOST nodes
- Power supply voltage to MOST transceivers (Vbat)
- Module presence/heartbeat (node heartbeat messages)
Diagnostic algorithm
- Read and record all U codes and related module DTCs; capture freeze frame and timestamp. 2) Confirm battery/charging health: measure voltage at rest and during cranking; ensure stable supply (>12V nominal). 3) Inspect all visible MOST fiber connectors and harness areas for damage or contamination; reseat connectors. 4) Check fuses and power/ground circuits for head unit, amplifier and gateway; repair any faults. 5) With a MOST-capable diagnostic tool, list MOST topology and node statuses; identify any node reporting an unlocked/unauthorized state or high error counters. 6) If a specific module shows persistent errors, attempt to reinitialize or reflash module software to correct version using dealer procedures. 7) If fault follows a recent software update or module replacement, verify programming completed and node security keys (if applicable). 8) If physical damage to fiber or connectors is found, repair/replace affected harness/components and re-check ring continuity. 9) After repairs or programming, clear DTCs and cycle ignition; confirm fault does not return under normal use. 10) If problem persists, escalate to dealer/MOST specialist for in-depth ring diagnostics or module replacement.
- similar_codes:[
- U1000
- U0073
- U0100
- U0140
- U0401
Likely causes
- Loose/damaged MOST fiber optic connectors or cable
- Faulty head unit or MOST transceiver module
- Recent software reflash or incomplete programming of a MOST node
- Intermittent battery/charging system voltage drop during module communication
Fault status
Status
MOST Critical Unlock Detected — a MOST network node reported an unexpected unlock/authorization or network security fault. Potential loss of multimedia functions. Further inspection and dealer-level diagnostics recommended.
Repair difficulty: Hard
Diagnostic time: 2.0 - 4.0 hours
Similar codes
Repair manuals
Manual library for HYUNDAI
84
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