What does DTC fault code B0004 mean?
The B0004 fault code, applicable to all car manufacturers, means “Driver Knee Bolster Deployment Control (Subfault)“.
Background Information: Knee airbags are typically located at the bottom of the steering wheel and near the passenger-side glove box. Their function is to protect the driver’s and passenger’s knees and legs during a collision. More and more new cars are equipped with driver knee airbags, while passenger knee airbags are still not widely used.
Symptoms of B0004:
- The airbag warning light illuminates on the dashboard.
- The knee brace fails to deploy upon impact.
- An airbag system malfunction warning sound plays.
- Diagnostic fault code B0004 is stored in the vehicle’s computer memory.
Common Causes of B0004:
- Sensor malfunction detecting a collision.
- Wiring problem or damaged wiring harness.
- Control module malfunction.
- Mechanical failure of the deployment mechanism.
- Water or moisture intrusion causing corrosion.
How to Fix B0004:
- First, use a professional OBD2 scanner to diagnose the specific cause of the B0004 code.
- Check the collision-detecting sensors for damage or signs of malfunction.
- Check the wiring harness for breaks, wear, or corrosion; repair or replace if necessary.
- Test the control module for proper function; replace if faulty.
- Check the deployment mechanism for mechanical failure; repair or replace if necessary.
B0004 Frequently Asked Questions
What is the purpose of the B0004 driver’s knee airbag?
The B0004 driver’s knee airbag is designed to protect the driver’s lower limbs in a collision. Deployed in a frontal collision, it reduces the risk of serious injury by cushioning the impact and helping the driver maintain a safe posture, thus preventing knee injuries.
How much does it cost to install or replace a B0004 airbag system?
The cost of installing or replacing a B0004 airbag system varies significantly depending on the vehicle model and labor rates. Typically, parts costs between $100 and $500, and labor costs may add another $100 to $300, resulting in a total estimated service cost between $200 and $800.
How often should the airbag system be inspected?
It is recommended that the airbag system, including the B0004 knee airbag, be inspected at least annually. Regular inspections can detect any malfunctions or problems and ensure that the airbags function properly in a collision. Some manufacturers may recommend more frequent inspections after major repairs.
Can the B0004 airbag deploy unexpectedly?
While rare, unexpected deployment can occur due to sensor system malfunctions or electrical issues. However, modern B0004 systems are designed with multiple safety features to minimize risk, ensuring the airbags deploy only in major collision scenarios.
What should I do if the airbag warning light is on?
If the airbag warning light on the dashboard is on, there may be a problem with the airbag system (including the B0004 knee airbag). It is crucial to have a qualified mechanic inspect your vehicle as soon as possible to diagnose and resolve any potential issues, ensuring your safety.
Is the B0004 airbag system compatible with all types of vehicles?
The B0004 airbag system is designed for specific vehicle models and types. Compatibility may vary depending on vehicle design and safety features. Always consult your vehicle manufacturer for specifications or a qualified mechanic before installation to confirm compatibility.
Tip: To quickly find the B0004 fault code, you can use a professional airbag code reader. This will help you accurately pinpoint the problem.