A short to ground on the bus E (+) wire, often caused by chafed insulation rubbing against metal; A faulty control module on bus E that is internally shorting the positive line to ground; Corroded or loose connector pins at any module on the bus, especially in areas exposed to moisture; Damaged wiring harness from rodent damage, accident repair, or improper previous repairs; A failed termination resistor inside one of the modules, which upsets the bus voltage levels; Low battery voltage or a poor ground connection that causes modules to behave erratically and pull the bus low; Aftermarket electronics improperly tapped into the bus wiring, creating an unintended load or short

DTC codes / U00xx · Network wiring and bus faults / U0067

U0067Vehicle Communication Bus E (+) Low

Q: What does code U0067 mean?

Vehicle Communication Bus E (+) Low. U0067 is a generic network communication code indicating that the vehicle's communication bus E positive circuit is reading low voltage, which means the control modules on that bus cannot exchange data reliably. The computer detected an abnormally low signal level on the bus E (+) wire, often because of a short to ground, a faulty module, or damaged wiring.

U0067 is a generic network communication code indicating that the vehicle's communication bus E positive circuit is reading low voltage, which means the control modules on that bus cannot exchange data reliably. The computer detected an abnormally low signal level on the bus E (+) wire, often because of a short to ground, a faulty module, or damaged wiring.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

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
The engine may crank but fail to start, or start and run poorly due to lost communication between modules
Intermittent or complete failure of accessories such as the radio, climate control, or power windows
The transmission may default to limp mode or shift erratically because it cannot receive sensor data
Often no symptoms besides the warning light if the fault is intermittent or affects a non-critical module
A no-start condition where the ignition is on but the engine does not crank because the start request cannot be communicated

Common causes, most likely first

A short to ground on the bus E (+) wire, often caused by chafed insulation rubbing against metal
A faulty control module on bus E that is internally shorting the positive line to ground
Corroded or loose connector pins at any module on the bus, especially in areas exposed to moisture
Damaged wiring harness from rodent damage, accident repair, or improper previous repairs
A failed termination resistor inside one of the modules, which upsets the bus voltage levels
Low battery voltage or a poor ground connection that causes modules to behave erratically and pull the bus low
Aftermarket electronics improperly tapped into the bus wiring, creating an unintended load or short

How to diagnose and fix it

Verify battery voltage and condition, and check that all ground connections for the affected modules are clean and tight
Use a scan tool to read all stored codes and identify which modules are offline or communicating intermittently on bus E
Disconnect the battery and measure resistance from the bus E (+) wire to ground at each module connector to look for a short
Inspect the wiring harness along its routing for chafing, corrosion, or rodent damage, especially near sharp edges and connectors
Isolate modules one at a time by disconnecting them and rechecking bus voltage to see if the low condition disappears
Repair or replace the damaged section of wire or the faulty connector, then clear codes and verify communication is restored
If a module is found to be internally shorting the bus, replace that module and perform any required programming or initialization

When bus E reads low but modules test fine

A common oversight is blaming the module that sets the code when the actual short is in a different module on the same bus, so disconnecting modules one by one is the fastest way to isolate the culprit.
Bus E is often a medium-speed data bus used for body and convenience functions, so a fault here may not disable the engine but can cause strange accessory behavior that drivers ignore until the battery drains.
Water intrusion into a connector or module housing can create a partial short that only appears in damp weather, making the code intermittent and hard to reproduce in a dry shop.
Aftermarket alarms, remote starters, or dash cameras tapped into the bus wiring are frequent causes of a low bus E (+) signal that owners never suspect.
A weak battery or failing alternator can cause modules to drop offline and set U0067 without any actual wiring fault, so always load-test the battery before chasing wires.

Can I keep driving with U0067?

If the vehicle starts and runs normally, you can drive it to a repair shop, but avoid long trips and expect that accessories or safety systems may stop working without warning. If the engine will not start or the transmission is in limp mode, do not drive and have the vehicle towed.

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.