OBD Guide

U0042

Vehicle Communication Bus B (-) Open

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$6–56 (est.)

Symptoms

  • Check Engine light comes on
  • Loss of communication between some modules
  • Incorrect operation of systems using the CAN bus
  • Errors in other vehicle systems
  • Possible problems with diagnostics

Causes

  • CAN B bus wire break (-)
  • Poor contact in connectors
  • Short circuit in the circuit
  • Failure of one of the modules on the bus
  • Wiring harness damage

How to Fix

  1. Check the integrity of the CAN B bus wires (-)
  2. Inspect connectors for oxidation or damage
  3. Check the resistance in the circuit
  4. Diagnose modules connected to the bus
  5. If necessary, replace damaged wires or connectors

Related codes

Error U0042 by Vehicle Brand