Airbag sensors are distributed around the vehicle: front crash sensors sit in the engine bay near the corners of the bumper, side impact sensors live in the doors or around the pillars, and the system’s control module plus seat-occupancy sensors are tucked under the dash or inside the seats. If the airbag warning light is on, have a qualified technician diagnose the system.
Front crash sensors
These sensors monitor deceleration at the front and trigger the front airbags on impact. Locations typically include the left and right crash sensors mounted near the front bumper reinforcement or behind the radiator support, inside the engine bay on each side.
- Left front crash sensor (driver side) near the left bumper reinforcement
- Right front crash sensor (passenger side) near the right bumper reinforcement
- Sometimes located behind the bumper cover or within the bumper frame rail
Front crash sensors are usually mounted in the frame rails at the corners of the engine bay, designed for rapid response to frontal impacts.
Side impact sensors
These sensors detect side collisions and trigger side airbags and curtain airbags. Locations vary by vehicle but commonly include the door-mounted sensors and/or pillars (A-pillar or B-pillar) near the height of the seats.
- Door-mounted side impact sensors in each front door
- Pillar-mounted sensors in the A or B pillar near the front seats
- Curtain/roof rail sensors in some designs near the top of the door frame
Side sensors are integrated into structural members and may be inside door panels or attached to the pillars, depending on the car’s design.
Airbag control module and wiring
The SRS (airbag) control unit coordinates signals from all sensors and activates airbags. It is typically located under the dash, behind the glove box on the passenger side, or in the center console area, with related electrical harnesses running to all sensors.
- SRS control module/ECU
- Wiring harnesses routed through the dash, under seats, and through the pillars
- Diagnostic port used by technicians
Access to the control module and wiring should be handled only by trained professionals using proper diagnostic tools.
Seat occupancy and knee airbags
Some systems include a passenger seat occupancy sensor to prevent deployment of the passenger airbag when the seat is empty or lightly occupied. Knee airbags have sensors and actuation integrated with the lower dash area and under the seats in some models.
- Passenger seat occupancy mat with weight sensor
- Driver knee airbag area under the dash near the steering column
- Passenger knee airbag area under the dash or glove box
These components may be integrated into the seat frame, seat cushion, or lower dash to ensure appropriate deployment during frontal impacts.
What to do if the airbag light is on
If the airbag warning light is illuminated, stop driving if possible and arrange a professional diagnostic check. Do not attempt to repair, disable, or remove components yourself—the system is a safety-critical feature and improper handling can cause injury or incorrect deployment.
Summary
Airbag sensors are spread across a vehicle: front crash sensors in the engine bay corners, side impact sensors in doors and pillars, a centralized control module under the dash or in the center console, and seat/occupant sensors built into the seats. A warning light warrants prompt professional diagnosis to ensure proper deployment in a crash.