Vehicle Trouble Codes and Diagnostics

The OBD-II code B0004 signifies a malfunction in the Driver Knee Bolster Deployment Control system, which is part of the vehicle's airbag or supplemental restraint system (SRS). This code points to a problem with the circuit that controls the deployment of the knee bolster airbag. The issue may stem from electrical faults, sensor malfunctions, or defects in the deployment mechanism.

Symptoms:

Airbag Warning Light, Deactivated Airbag System or Other Warning Messages

Possible Causes of B0004 Code :

• Defective Knee Bolster Airbag Module: The knee bolster airbag may be faulty.
• Damaged Wiring or Connectors: Loose, corroded, or damaged wiring in the airbag system can result in communication issues.
• Faulty Sensors: Sensors responsible for monitoring the deployment mechanism may be malfunctioning.
• Electrical Issues: A short circuit or open circuit in the deployment system can disrupt functionality.
• Airbag Control Unit (ACU) Malfunction: The module that controls airbag deployment may have failed.

How to Fix It?

Be sure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

Common Diagnoses and Repairs:

• Scan for Diagnostic Trouble Codes (DTCs): Use a professional OBD-II scanner to retrieve all stored codes to check for related issues with the airbag system.
• Inspect Airbag System Wiring: Check for any loose connections, damaged wiring, or corroded terminals in the airbag circuit.
• Check the Knee Airbag and Sensor: Inspect the knee airbag module and related sensors for proper function.
• Test the Airbag Control Module: If necessary, test or replace the Airbag Control Module, as it may not be sending the proper signals to the knee bolster airbag.
• Reset and Test: After addressing the issue, reset the code using the scanner and test the system to verify that the issue is resolved.