A short to voltage on the CAN D (+) wire, often caused by chafed insulation contacting a power wire; A faulty control module internally shorting the D (+) line to battery voltage; Corrosion or damage in a connector that allows the D (+) terminal to touch a power terminal; Aftermarket accessories improperly wired into the CAN bus circuit; A defective CAN transceiver inside one of the modules on the network

DTC codes / U00xx · Network wiring and bus faults / U0059

U0059Vehicle Communication Bus D (+) High

Q: What does code U0059 mean?

Vehicle Communication Bus D (+) High. U0059 is a generic network communication code indicating that the vehicle's main communication bus, often called the CAN (Controller Area Network) bus, has a short to voltage on the D (+) data line. The computer that set this code detected an abnormally high voltage on the positive data wire, which prevents reliable data exchange between control modules.

U0059 is a generic network communication code indicating that the vehicle's main communication bus, often called the CAN (Controller Area Network) bus, has a short to voltage on the D (+) data line. The computer that set this code detected an abnormally high voltage on the positive data wire, which prevents reliable data exchange between control modules.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaNetwork wiring and bus faults

Symptoms you may notice

Illumination of the check engine light or a dedicated communication warning light
Multiple warning lights on the dashboard, such as ABS, traction control, and airbag
Intermittent or complete failure of various electronic systems, including dashboard displays and climate control
The engine may start and run, but other modules may be unresponsive
Often no symptoms besides the warning light, especially if the fault is intermittent

Common causes, most likely first

A short to voltage on the CAN D (+) wire, often caused by chafed insulation contacting a power wire
A faulty control module internally shorting the D (+) line to battery voltage
Corrosion or damage in a connector that allows the D (+) terminal to touch a power terminal
Aftermarket accessories improperly wired into the CAN bus circuit
A defective CAN transceiver inside one of the modules on the network

How to diagnose and fix it

Use an OBD-II scan tool to read all stored codes and identify which modules are communicating and which are not
Visually inspect the CAN D (+) wiring harness for damage, chafing, or corrosion, especially near connectors and high-vibration areas
Disconnect the battery and measure resistance from the D (+) wire to battery positive and to ground to check for a short
Isolate modules one by one by disconnecting them and rechecking the bus voltage to see if the short disappears
Repair any damaged wiring or replace corroded connectors, then clear codes and verify communication is restored
If a module is found to be internally shorted, replace or repair that module and recheck the network

Don't replace modules before checking the wiring

A common mistake is to replace the module that set the code, but the fault often lies in the wiring harness or a connector rather than the module itself.
The D (+) line is one of two CAN bus wires; a short to voltage on it can be caused by a nearby power wire that has rubbed through its insulation.
Aftermarket installations such as alarms, radios, or telematics devices are frequent culprits for introducing voltage into the CAN bus.
Intermittent U0059 codes can be caused by loose pins in a connector that make contact only under certain vibration or temperature conditions.
Some vehicles will set U0059 if the battery voltage is excessively high, so always check charging system voltage before diving into network diagnostics.

Can I keep driving with U0059?

If the vehicle runs and drives normally, you can drive it to a repair shop, but avoid relying on advanced driver aids and be prepared for possible communication failures. If multiple systems are malfunctioning or the engine stalls, stop driving and have the vehicle towed to prevent unsafe operation.

Tools that help

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