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DTC codes / U00xx · Network wiring and bus faults / U0062

U0062Vehicle Communication Bus D (-) High

U0062 is a generic network communication code indicating that the vehicle's Controller Area Network (CAN) data bus, specifically the D (-) or low-speed negative side, is experiencing a high voltage condition. The computer detected that the CAN D- wire is stuck at a voltage above its normal operating range, which disrupts communication between modules.

SystemNetwork
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaNetwork wiring and bus faults

Symptoms you may notice

  • Multiple warning lights illuminated on the dashboard, often including the check engine light, ABS, and traction control.
  • Intermittent or complete failure of various electronic systems such as radio, climate control, or power windows.
  • The engine may start but run poorly or stall, or the vehicle may fail to start altogether.
  • Communication with the scan tool may be lost or erratic, preventing access to some modules.
  • Often no symptoms besides the warning light if the fault is intermittent or affects only non-critical modules.

Common causes, most likely first

  1. A short to voltage on the CAN D- wire, often due to chafed insulation contacting a power wire.
  2. A faulty module connected to the CAN D- bus that is internally shorted and pulling the line high.
  3. Corroded or damaged connectors at the CAN D- bus, causing high resistance or intermittent shorts.
  4. An open or high-resistance ground connection for a module on the network, causing the bus to float high.
  5. A defective CAN transceiver inside one of the modules, leading to improper bus voltage levels.
  6. Aftermarket accessories improperly wired into the CAN bus, introducing voltage spikes or shorts.

How to diagnose and fix it

  1. Use an OBD-II scan tool to read all stored codes and confirm U0062 is current; clear codes and test-drive to see if it returns.
  2. Measure voltage on the CAN D- pin (usually pin 14) at the diagnostic link connector (DLC) with the key on and engine off; normal voltage is around 2.5 volts, so a reading above 3.5 volts indicates a high condition.
  3. Disconnect modules one by one while monitoring the CAN D- voltage to isolate which module is pulling the bus high.
  4. Inspect the CAN D- wiring harness for signs of damage, chafing, or contact with power wires, especially near sharp edges or moving components.
  5. Check and clean all grounds related to modules on the CAN bus, ensuring they are tight and free of corrosion.
  6. If a faulty module is identified, replace or repair it, then clear codes and verify communication is restored.
  7. Perform a voltage drop test on the CAN D- circuit to detect excessive resistance that could mimic a high voltage condition.

Hidden causes of CAN D- high voltage

  • A common oversight is blaming the wiring harness first, but a module with an internal short to power can hold the entire bus high, so unplugging modules is a faster diagnostic step.
  • The CAN D- line is normally biased to about 2.5 volts; a high reading often means another module is transmitting abnormally or a short to a 5-volt reference wire exists.
  • Aftermarket alarms or remote starters tapped into the CAN bus are frequent culprits, and disconnecting them often resolves the code without further repair.
  • This code can set intermittently due to a loose ground at a single module, which may not show up in static voltage checks but appears during vibration or temperature changes.
  • U0062 does not always indicate a hard failure; it can be stored by a transient voltage spike during jump-starting or battery replacement, so clearing and rechecking is a valid first step.

Can I keep driving with U0062?

If the vehicle runs and drives without noticeable issues, you may drive it cautiously to a repair shop, but avoid long trips or heavy electrical loads. If multiple systems are malfunctioning or the engine stalls, stop driving and have the vehicle towed to prevent unsafe operation.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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