What does error 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.

Tip: To quickly find the B0004 fault code, you can use a professional airbag code reader. This will help you accurately pinpoint the problem.