Damaged or chafed wiring on the bus E (+) circuit, causing a short to voltage or an open circuit; Poor or corroded electrical connector at a module or inline splice on the bus E (+) line; Faulty module internally shorting the bus E (+) line to power or ground; Water intrusion into a connector or module, leading to corrosion and high resistance; Aftermarket accessory improperly tapped into the bus E (+) wire, introducing voltage spikes; Loose or damaged ground connection for a module on the bus E network

DTC codes / U00xx · Network wiring and bus faults / U0068

U0068Vehicle Communication Bus E (+) High

Q: What does code U0068 mean?

Vehicle Communication Bus E (+) High. U0068 is a generic network communication code indicating that the vehicle's communication bus E, specifically its positive (+) circuit, is reading a high voltage condition. The computer or gateway module detected an abnormally high signal level on the bus E (+) wire, which can disrupt data exchange between modules and trigger the warning light.

U0068 is a generic network communication code indicating that the vehicle's communication bus E, specifically its positive (+) circuit, is reading a high voltage condition. The computer or gateway module detected an abnormally high signal level on the bus E (+) wire, which can disrupt data exchange between modules and trigger the warning light.

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 fault warning
Multiple dashboard warning lights (ABS, airbag, traction control) due to lost module communication
Intermittent or complete failure of electronic features such as radio, climate control, or power windows
Engine may run poorly or stall if the powertrain control module loses communication with other modules
Often no symptoms besides the warning light, especially if the fault is intermittent or affects a non-critical module

Common causes, most likely first

Damaged or chafed wiring on the bus E (+) circuit, causing a short to voltage or an open circuit
Poor or corroded electrical connector at a module or inline splice on the bus E (+) line
Faulty module internally shorting the bus E (+) line to power or ground
Water intrusion into a connector or module, leading to corrosion and high resistance
Aftermarket accessory improperly tapped into the bus E (+) wire, introducing voltage spikes
Loose or damaged ground connection for a module on the bus E network

How to diagnose and fix it

Use an OBD-II scan tool to read all stored codes and identify which modules are offline or reporting communication errors
Inspect the bus E (+) wiring and connectors for visible damage, corrosion, or loose pins, starting at the diagnostic link connector (DLC) and working toward each module
Measure voltage on the bus E (+) circuit with a digital multimeter (DMM) with the key on and engine off, comparing to the manufacturer's specification (typically around 2.5 to 3.5 volts for a differential bus)
Perform a resistance check on the bus E (+) line with the battery disconnected to look for shorts to power or ground
Disconnect modules one at a time to see if the high voltage condition disappears, isolating the faulty module
Repair or replace damaged wiring, connectors, or the faulty module as needed, then clear codes and verify communication is restored
Road test the vehicle and re-scan to confirm the code does not return

Bus E high voltage misdiagnosis traps

A high voltage on bus E (+) is often caused by a module that is internally shorted to battery voltage, not by a wiring fault, so disconnecting modules one by one is a reliable isolation method.
The code can set intermittently due to a loose ground connection at a module, which may not show up during a simple voltage check unless the circuit is loaded.
Aftermarket alarms, remote starters, or phone chargers plugged into the DLC can backfeed voltage onto the bus and trigger U0068 without any factory defect.
Bus E is not used on every vehicle; some manufacturers use different bus designations, so always confirm the bus topology in the service information before probing wires.
A weak or failing battery can cause voltage spikes that mimic a bus E (+) high fault, so load-test the battery before replacing expensive modules.

Can I keep driving with U0068?

If the vehicle runs and drives normally, you can drive it to a repair shop, but avoid long trips or towing until the fault is diagnosed. If multiple warning lights are on or the engine runs poorly, stop driving and have the vehicle towed to prevent safety system failures.

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.