U0091

Vehicle Communication Bus G (-) shorted to Bus G (+)

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$6–56 (est.)

Symptoms

Unstable operation of the dashboard
Lost connection with some vehicle systems
The Check Engine light comes on
Problems starting the engine
Malfunctions of electronic systems

Causes

Damage to the CAN bus wiring harness
Short circuit in one of the ECUs
Damaged or oxidized connectors
Faulty relays or fuses
Mechanical damage to wiring

How to Fix

Check the integrity of the CAN bus wiring harness
Inspect all connectors for damage and oxidation
Check the functionality of all associated computers
Use an oscilloscope to diagnose CAN bus signals
Replace damaged wiring sections

Related codes

U0100 U0121 U0140