OBD Guide

U0039

Vehicle Communication Bus B (+) Open

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$6–56 (est.)

Symptoms

  • Check Engine Light Is On
  • Malfunction of related systems (for example, airbags)
  • Lost communication with one or more modules
  • Incorrect dashboard readings

Causes

  • Bus B wire break (+)
  • Poor contact in the connector
  • Corrosion or oxidation of contacts
  • Malfunction of one of the modules in the network
  • Wiring harness damage

How to Fix

  1. Check the continuity of the Bus B wire (+)
  2. Inspect and clean the contacts in the connectors
  3. Check connections between modules
  4. Scan all modules for errors
  5. Repair only from an authorized dealer

Related codes

Error U0039 by Vehicle Brand