U0033

Vehicle Communication Bus A (-) Open

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$6–56 (est.)

Symptoms

Check Engine Light Is On
Disabling some car systems (ABS, ESP, airbags)
Problems starting the engine
Incorrect operation of the dashboard
Communication errors in other modules

Causes

CAN A bus wire break (-)
Short circuit in CAN line
Oxidation of contacts in connectors
Malfunction of one of the network modules
Mechanical damage to the wiring harness

How to Fix

Visually inspect the wiring harness for damage
Checking the integrity of the CAN A (-) line with a multimeter
Cleaning contacts in CAN bus connectors
Checking line resistance
Replacing a damaged section of wiring

Related codes

U0001 U0023 U0100