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Home / DTC / U1971 — Multimedia CAN Single Line Error

U1971 — Multimedia CAN Single Line Error

Detailed page for trouble code U1971.

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U1971

HYUNDAI U — Network/User

Multimedia CAN Single Line Error

Brand: HYUNDAI
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in CAN_H or CAN_L wiring to the multimedia/AVN module
  • Poor connector pin contact or corroded connector at multimedia unit or junctions
  • Short to battery voltage or ground on one CAN line
  • Missing or failed CAN termination resistor (open or incorrect value)
  • Faulty multimedia (AVN) module CAN transceiver
  • Water intrusion or physical damage to harness near doors/dash

Symptoms

  • No audio, blank or frozen AVN screen
  • Navigation, Bluetooth, vehicle settings or phone functions not available
  • Multiple CAN communication DTCs or U-codes present
  • Intermittent operation of infotainment features
  • Error message on cluster or infotainment about communication failure

What to check

  • Read all stored U- and related DTCs and note freeze frame / occurrence
  • Visually inspect multimedia unit connector, harness, and nearby wiring for damage or corrosion
  • Check battery/charging system voltage for stability during tests
  • Verify CAN termination resistor (approx. 60 ohms across CAN_H and CAN_L)
  • Measure CAN line voltages with ignition ON (see signal params)
  • Use an oscilloscope to view CAN bus waveform if available

Signal parameters

  • Recessive (idle) state: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (within ±0.5 V)
  • Dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
  • Differential voltage (CAN_H − CAN_L) ≈ 0 V idle, ≈ 2.0 V dominant
  • Bus termination: approx. 60 Ω across CAN_H and CAN_L (two 120 Ω in parallel)
  • Typical high-speed CAN bit rate often 500 kb/s (confirm vehicle spec)

Diagnostic algorithm

  1. Retrieve all DTCs with a scan tool, note occurrence history and related U-codes.
  2. Check vehicle battery voltage and ground connections to ensure stable supply during diagnostics.
  3. Visually inspect multimedia unit connector and harness for damage, corrosion, or water intrusion. Repair any visible faults.
  4. With ignition ON (engine off), measure CAN_H and CAN_L voltages at the multimedia connector. Compare to expected signal params.
  5. Measure resistance between CAN_H and CAN_L with power off; expect ≈60 Ω. If open or out of range, trace harness for open or missing termination.
  6. Probe bus with an oscilloscope while operating the network (e.g., turn ignition/accessory ON) to observe waveform integrity and identify stuck dominant/recessive states or excessive noise.
  7. Disconnect the multimedia unit and check if the bus returns to normal. If removing the module clears the fault, suspect module transceiver or internal failure.
  8. Inspect and test continuity from the multimedia connector to other nodes/junctions. Wiggle harnesses and connectors while watching the bus for changes to locate intermittent faults.
  9. Remove/disable aftermarket devices that tie into the CAN or power near the AVN and re-test.
  10. If wiring and connectors test good, consider replacing or repairing the multimedia module or its CAN transceiver. Check and apply any OEM software updates before replacement.
  11. After repair, clear DTCs and verify repair by road test and re-scan for reappearance of U1971 or related codes.

Likely causes

  • Damaged or disconnected CAN wiring between multimedia unit and CAN junction
  • Corroded/loose connector at multimedia unit or body harness
  • Failed CAN transceiver inside multimedia module
  • Open/missing termination or incorrect resistance on bus
  • Short to battery or ground on one of the CAN lines

Fault status

⚠️ Status
Multimedia CAN single-line error — abnormal CAN_H/CAN_L behavior detected on AVN/multimedia network (open/short/voltage fault).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 3.0 hours

Similar codes

U0073 U0100 U0140 U1000 U0293
371

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