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Home / DTC / U0067 — Vehicle Communication Bus E (+) Low

U0067 — Vehicle Communication Bus E (+) Low

Detailed page for trouble code U0067.

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Code

U0067

HYUNDAI U — Network/User

Vehicle Communication Bus E (+) Low

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

Causes

  • Damaged or shorted CAN/communication wiring (Bus E +)
  • Failed module or CAN transceiver pulling the bus low
  • Poor or corroded connector or ground connection
  • Missing or failed termination resistor
  • Low battery/poor battery connections or charging system issues
  • Water intrusion or physical damage at a connector or splice

Symptoms

  • Loss of functionality or intermittent operation of systems on Bus E (infotainment, gateways, sensors, etc.)
  • Multiple related U-codes or module communication errors
  • Intermittent or no response from specific control modules
  • Malfunction indicator lamps or system warnings illuminated
  • Erratic behavior of affected systems (e.g., display blanking, feature disablement)

What to check

  • Read all stored and pending U- and manufacturer codes and note related modules
  • Check battery voltage and charging system (engine off and cranking)
  • Visually inspect wiring harnesses, connectors, and grounds for damage, corrosion, or water ingress
  • Check continuity and resistance between CAN Bus E + and ground/power with ignition off
  • Measure termination resistance across Bus E (CAN_H to CAN_L) — expect ~60 ohms for two 120Ω terminators in parallel
  • Use a scan tool to monitor live data and verify which modules are not responding

Signal parameters

  • Idle/recessive voltage: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (both near mid-supply)
  • Dominant state voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
  • Bus termination resistance: approximately 60 Ω across CAN_H and CAN_L (two 120 Ω terminators in parallel)

Diagnostic algorithm

  1. Capture all fault codes and freeze-frame data; record affected modules and time stamps.
  2. Verify battery voltage and charging system; correct low-voltage issues before further testing.
  3. Perform a careful visual inspection of Bus E wiring, connectors, and modules for damage or corrosion; repair obvious issues.
  4. With ignition off, measure resistance between CAN_H and CAN_L at convenient connector — expect ~60 Ω. If open or very high, check for disconnected terminator or open circuit.
  5. With ignition on (no cranking), measure DC voltages of CAN_H and CAN_L relative to vehicle ground at multiple points on Bus E. Look for a stuck-low CAN_H (significantly below expected idle) or other anomalies.
  6. Use an oscilloscope to inspect CAN waveforms while communicating modules are active. Look for missing dominant pulses, clipped waveforms, excessive noise, or a line held low.
  7. Disconnect suspected modules one at a time (or isolate segments per wiring diagram) to identify a module that clears the fault when removed. Do not disconnect modules required for safety while driving.
  8. If a module is identified, verify its power and ground circuits and wiring. Replace module or repair wiring as appropriate.
  9. Repair any damaged wiring/connectors and replace missing/failed termination resistors. Reconnect and secure harnesses to prevent future chafing or water intrusion.
  10. Clear codes, perform a full system scan and test drive to confirm the fault does not return. Recheck signals if intermittent.

Likely causes

  • Short to ground on Bus E + conductor
  • Faulty ECU/module on the Bus E network with internal transceiver failure
  • Open or high-resistance connection at a splice or connector on Bus E +
  • Failed or removed termination resistor causing abnormal voltages
  • Low battery/charging system causing undervoltage to modules

Fault status

⚠️ Status
Vehicle Communication Bus E (+) Low — voltage on the Bus E positive line is below expected range, causing communication errors on that network.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0073 U0100 U0101 U0121 U0140
371

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