U0040

Vehicle Communication Bus B (+) Low

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$17–56 (est.)

Symptoms

Incorrect operation of systems connected to the CAN B bus
Malfunction indicator light comes on
Problems with climate control
Errors in other systems related to the CAN B bus

Causes

Open or short circuit in the CAN B bus circuit
Wiring harness damage
Malfunction of one of the modules connected to the CAN B bus
Corrosion or poor contact in connectors
Problems with module power supply

How to Fix

Check the integrity of the CAN B bus wiring harness
Inspect connectors for corrosion or damage
Check the power supply of the modules connected to the CAN B bus
Diagnose faulty modules using a scanner
Repair only from an authorized dealer

Related codes

U0041 U0042 U0043