U0030

Vehicle Communication Bus A (+) Open

Severity

🔴 High

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$6–56 (est.)

Symptoms

Loss of communication between ECUs
Inoperative vehicle systems (e.g. ABS, airbags)
Check Engine light comes on
Unstable engine operation
Problems with diagnostics via OBD-II

Causes

Broken wire in CAN A bus (+)
Poor contact in CAN bus connectors
Short circuit in CAN circuit
Malfunction of one of the ECUs
Wiring harness damage

How to Fix

Check the integrity of the CAN A bus wires (+)
Inspect the CAN bus connectors for oxidation or damage.
Check the resistance and voltage in the CAN circuit
Diagnose the ECU for faults
Replace damaged wires or connectors

Related codes

U0029 U0031 U0100