OBD-II Standard OBD-II Universal Error Code B0403

OBD-II Standard OBD-II Major Body

Model: OBD-II Universal | Code: B0403

Applicable Systems
OBD-II

Symptoms

An interior light may not function correctly. The body control module detects a dome/map light circuit fault. DTC B0403 is stored in the body control module.

Possible Causes

  • Interior lamp bulb failure
  • Door jamb switch faulty
  • Body control module output fault
  • Interior lamp wiring short to ground

Troubleshooting Steps

  1. Step 1: Connect a diagnostic scanner and read body DTCs to confirm B0403
    DTC B0403 is present with freeze frame data
  2. Step 2: Inspect wiring and connectors in the affected circuit
    Wiring intact, connectors clean and properly seated
  3. Step 3: Perform component-level testing per manufacturer diagnostic procedure
    Component values within specification or component confirmed faulty
  4. Step 4: Clear the DTC and verify it does not return
    DTC does not return after system self-test

How to Reset

Clear the DTC after repair using a diagnostic scanner. The code will clear automatically if the fault is no longer detected after 3 consecutive drive cycles.

Common Replacement Parts

  • varies: Interior lamp bulb (per affected light) (Confirm part number via VIN before ordering)

Frequently Asked Questions

  • Q: What does code B0403 mean?

    This is a body-related diagnostic trouble code indicating an issue with the body system. The specific component should be diagnosed per the manufacturer's procedure.

  • Q: Is code B0403 safe to ignore?

    If the code relates to the airbag system (SRS), it is NOT safe to ignore as airbags may not deploy in a crash. For other body systems, the vehicle can typically be driven but the affected feature may not work.

Related OBD-II Standard Fault Codes

Source: SAE J2012 Standard OBD-II Diagnostic Trouble Codes

Category: OBD-II