2021 BMW 840i Air Bag Occupant Sensor Replacement Cost

Most modern vehicles equipped with airbags will monitor the position of passengers, most commonly in the front passenger seat. This is done to prevent unnecessary airbag deployment in the event of a collision, and therefore save repair cost to the vehicle. These sensors are pressure sensitive, and are placed inside the seat or seat frame so when an occupant sits on the seat the sensor activates the airbags for that seating position.

Air bag occupant sensors, as mentioned, are installed in the seat to measure when a passenger is in that seating position. This allows the airbag control module to activate the airbags in that position when needed or deactivate the airbags in that position when they are not. This is an autonomous system that takes the place of older systems where the key is needed to turn the airbags on and off for the passenger seating position. When a person or items of sufficient weight are placed on the seat, an indicator typically advises the driver and passenger that the passenger airbags are on, and will inflate in the event of an emergency.

Failing occupant sensors can show one of two symptoms. They may stay on at all times, causing the passenger airbags to stay active even when a passenger is not present. Also, they may not operate at all, which prevents the airbags from activating when a passenger is seated in that seating position. Also, for most systems, the airbag or SRS warning light will illuminate on the instrument cluster, prompting the driver to service the system.

Any time the supplemental restraint system (SRS) or airbag system is not functioning perfectly the risk to occupants increases in the event of a collision. These systems have been proven to protect occupants lives in the event of a collision, and should not be allowed to fall into disrepair. Also, most state or federal inspection programs will not pass a vehicle with the airbag or SRS warning lights illuminated during normal operation.