What does the B004B fault code mean?
The B004B fault code, applicable to all car manufacturers, means “Third Row Right Frontal Stage 3 Deployment Control (Subfault)“.
Background Information: Newer vehicles use multi-stage airbags to regulate the pressure inside the airbag. The higher the pressure, the greater the intensity of the airbag deployment. The system automatically determines the airbag deployment intensity based on parameters such as collision intensity, passenger weight, seat belt usage, child seat presence, and distance from the airbag. This design ensures that the airbag deploys at medium intensity in most collisions, reserving maximum intensity for the most severe collisions.
Common symptoms when B004B is present:
- The airbag warning light on the dashboard is illuminated.
- A diagnostic trouble code (DTC) is stored in the vehicle’s computer system.
- The airbag system cannot be reset after attempting to clear the fault code.
- The third-row right front airbag intermittently or fails to deploy during testing.
Most common causes of B004B:
- Faulty third-row right front stage 3 deployment control module.
- Wiring or electrical connection problems in the airbag system.
- The third-row right airbag sensor is impacted or damaged.
- Software or programming issues in the airbag control module.
- Overall wear and tear of airbag system components.
How to diagnose and repair the B004B fault code?
- First, use a professional OBD2 scanner diagnostic tool to diagnose the specific cause of the B004B code.
- Check the wiring and electrical connections of the airbag system for damage or corrosion.
- Test the third-row right front airbag sensor for proper function and replace if necessary.
- If the third-row right front stage 3 deployment control module is found to be faulty, replace it.
- Clear the diagnostic trouble code from the vehicle’s computer system and perform a comprehensive test of the airbag system to ensure proper airbag deployment. SRS “Airbag” and Seatbelt Pretensioner Service Precautions
Do not probe the electrical connectors on the airbags, side curtain modules, or seatbelts.
Do not disassemble or tamper with the seatbelt buckle/pretensioner, adaptive load limiter, seatbelt inflator, or probe the electrical connectors.
Do not use electrical testing equipment to check the SRS circuit unless instructed to do so in this service manual.
Before servicing the SRS, turn off the ignition switch, disconnect both battery cables, and wait at least 3 minutes. The airbags and seatbelt pretensioners may still deploy for approximately 3 minutes after the cables are removed. Therefore, do not touch any SRS connectors or wiring for at least 3 minutes.
Failure to follow these instructions may result in unintended module deployment, increasing the risk of serious personal injury or death.