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Home / DTC / U1972 — Multimedia CAN Limp Home Status

U1972 — Multimedia CAN Limp Home Status

Detailed page for trouble code U1972.

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Code

U1972

HYUNDAI U — Network/User

Multimedia CAN Limp Home Status

Brand: HYUNDAI
Type: U — Network/User
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Page language: EN

Causes

  • Open or short in multimedia CAN wiring (CAN H or CAN L)
  • Poor power or ground to the multimedia unit or gateway
  • Faulty multimedia head unit or CAN transceiver
  • Missing or damaged termination resistor(s) on the CAN bus
  • Water intrusion or corrosion at connectors behind dash
  • Aftermarket audio/telematics devices interfering with the bus

Symptoms

  • Multimedia system displays error or reduced functionality (audio, navigation, Bluetooth may be limited)
  • ‘Limp-home’ message related to multimedia or CAN on the instrument cluster or head unit
  • Intermittent loss of media controls or frozen screen
  • Other modules may show related U-codes or lost-communication faults
  • No audio or partial operation after vehicle start

What to check

  • Read and record U1972 and any related U-codes and freeze frame data with a capable scan tool
  • Verify battery voltage is within specification (12–14.5 V) during testing
  • Visually inspect connectors and harnesses at the multimedia head unit, gateway, and nearby junctions for corrosion, water, or damage
  • Check fuses and power/ground circuits for the multimedia unit
  • Measure DC voltage at the multimedia unit power and ground pins
  • With key on (engine off), measure CAN line voltages: CAN H and CAN L should be approximately 2.5 V (recessive)

Signal parameters

  • Recessive idle voltage: CAN H ≈ 2.5 V, CAN L ≈ 2.5 V (each to ground)
  • Dominant (active) levels typically: CAN H ≈ 3.5 V, CAN L ≈ 1.5 V (differential ≈ 2 V)
  • Termination resistance across CAN H–CAN L: ~60 Ω (two 120 Ω terminators in parallel)
  • Typical bus bitrate: varies by network (confirm factory spec for the multimedia/CAN gateway)
  • Expected low DC leakage to ground or battery on each CAN line

Diagnostic algorithm

  1. Document stored codes and freeze frame. Clear codes and attempt to reproduce the fault to capture present data.
  2. Determine which modules share the multimedia CAN bus (gateway, head unit, telematics). Note any other U-codes indicating related communication loss.
  3. Perform visual inspection of connectors, look for water, corrosion, bent pins, or aftermarket splices. Repair any physical damage.
  4. Verify battery supply and ground at the head unit and gateway. Repair any low-voltage or poor-ground issues.
  5. With battery disconnected, measure resistance between CAN H and CAN L at the multimedia connector (expect ~60 Ω). If open or high, trace for missing termination.
  6. With key on, measure CAN H and CAN L voltages at connector. If voltages not near 2.5 V or one line pulled to 0 V/12 V, isolate wiring for short to ground or battery.
  7. Use an oscilloscope or CAN bus analyzer to view signals for error frames, bus-off events, or excessive noise. Note which node causes errors.
  8. Disconnect the multimedia head unit (and aftermarket devices) and re-check bus behavior. If bus returns to normal, suspect the head unit or its transceiver.
  9. If wiring and power/ground are good but fault persists, check for software updates or reprogramming procedures from the dealer/technical service bulletins.
  10. Replace the failed module or repair wiring as indicated by diagnostics. After repair, clear codes and road-test to confirm fault does not return.

Likely causes

  • Damaged/dented wiring harness in dash or A-pillar causing intermittent CAN signals
  • Loose or corroded multi-pin connector at the multimedia unit or gateway
  • Failed CAN transceiver inside the head unit or gateway module
  • Aftermarket alarm or head unit tied into CAN without proper isolation
  • Open/shorted termination resistor(s) (expected ~60 Ω across CAN H-L at rest)

Fault status

⚠️ Status
U1972 — Multimedia CAN: Limp Home Status (multimedia module limited due to CAN communication fault)
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5 - 4.0 hours

Similar codes

U0073 U0100 U0121 U0155
371

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