Serious — S4Toyota Corolla · economy tier
B0004 on Toyota Corolla
The B0004 diagnostic trouble code on a Toyota Corolla indicates driver knee bolster deployment control. For Toyota vehicles, this code is commonly triggered by faulty airbag module — most common cause, test before replacing or damaged or corroded wiring/connector in the airbag/srs (supplemental restraint) system circuit.
Can You Still Drive?
Drive to a shop soon. Risk of damage if ignored.
Estimated Repair Cost
$100 – $2,000
for Toyota Corolla
Common on This Vehicle?
The B0004 code is relatively common on Toyota vehicles and often appears alongside other diagnostic codes.
Symptoms on Toyota Corolla
- •Check Engine Light illuminated
- •Airbag/SRS warning light on — airbags may be disabled
- •Seat belt pretensioner may not deploy in a collision
- •Diagnostic trouble code (DTC) stored in module memory
Common Causes
- •Faulty airbag module — most common cause, test before replacing
- •Damaged or corroded wiring/connector in the airbag/SRS (supplemental restraint) system circuit
- •Blown fuse or faulty relay for the airbag/SRS (supplemental restraint) system
- •Poor ground connection — check and clean all related ground points
- •Control module fault — rare but possible, only consider after ruling out simpler causes