A short to battery voltage on the Vehicle Communication Bus B (+) wire, often due to chafed insulation or a pinched harness; A faulty control module internally shorting the bus line high; Corroded or damaged connector pins at a module or inline harness connector; Water intrusion into a connector or module causing conductive paths; Aftermarket accessories improperly tapped into the bus wiring; A failed terminating resistor or bias circuit within a module, though less common

DTC codes / U00xx · Network wiring and bus faults / U0041

U0041Vehicle Communication Bus B (+) High

Q: What does code U0041 mean?

Vehicle Communication Bus B (+) High. U0041 is a generic network communication code indicating that a control module has detected an abnormally high voltage on the Vehicle Communication Bus B (+) circuit, which is a dedicated data line used for controller area network (CAN) communication between modules. The computer sets this code when the bus voltage exceeds the expected high threshold, typically because the bus is shorted to power or a module is holding the line high.

U0041 is a generic network communication code indicating that a control module has detected an abnormally high voltage on the Vehicle Communication Bus B (+) circuit, which is a dedicated data line used for controller area network (CAN) communication between modules. The computer sets this code when the bus voltage exceeds the expected high threshold, typically because the bus is shorted to power or a module is holding the line high.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaNetwork wiring and bus faults

Symptoms you may notice

Illumination of the malfunction indicator lamp (MIL) on the dashboard
Multiple warning lights on the instrument cluster, such as ABS, traction control, or airbag
Intermittent or complete loss of communication with one or more control modules
Erratic operation of electronic features like power windows, radio, or climate control
The engine may start and run normally, or may crank but not start if the affected bus is critical
Often no symptoms besides the warning light if the fault is isolated to a non-essential module

Common causes, most likely first

A short to battery voltage on the Vehicle Communication Bus B (+) wire, often due to chafed insulation or a pinched harness
A faulty control module internally shorting the bus line high
Corroded or damaged connector pins at a module or inline harness connector
Water intrusion into a connector or module causing conductive paths
Aftermarket accessories improperly tapped into the bus wiring
A failed terminating resistor or bias circuit within a module, though less common

How to diagnose and fix it

Connect a scan tool and record all stored codes and freeze-frame data to identify which modules are offline or reporting the fault
Inspect the Vehicle Communication Bus B (+) wiring for visible damage, chafing, or signs of shorting to power, especially near harness bends and connectors
Disconnect modules one at a time to see if the bus voltage returns to normal, isolating the module that is holding the line high
Measure resistance and voltage on the bus with a digital multimeter (DMM) to check for shorts to voltage or abnormal bias
Repair or replace any damaged wiring, connectors, or the faulty module as determined by the isolation test
Clear the codes and perform a road test to verify the repair and ensure communication is restored

Before you condemn a control module

A short to voltage on the bus is often caused by a wire rubbing against a power wire in the same harness, so inspect the entire length of the harness, not just near the modules.
Disconnecting a module to see if the fault clears can be misleading if multiple modules are on the same bus segment; use a breakout box to isolate segments methodically.
The code can be set by a module that is not directly related to the bus in question, as a faulty module on another bus can back-feed voltage through a gateway.
Aftermarket alarms, remote starters, or phone chargers plugged into the data link connector (DLC) can introduce voltage spikes that mimic a short to power.
Always check for technical service bulletins (TSBs) for the specific vehicle, as some models have known harness routing issues that cause this code.

Can I keep driving with U0041?

If the vehicle runs and drives normally, you can drive it to a repair shop, but avoid using electronic features that may be affected and do not tow a trailer or use aftermarket accessories. If multiple warning lights are on 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.