The airbag cushion that protects occupants in a crash is only one part of a complex system that requires calibration and accuracy. When an airbag is deployed, it alters several of the components needed to ensure it functions as intended. Unfortunately, although it is expensive, this means that airbags cannot be repaired after they have deployed; they must be replaced entirely.
The airbag system is part of the vehicle’s Supplemental Restraint System, working with the seatbelts to ensure maximum occupant protection in crashes of all types. The most obvious airbag component is the airbag module, which is the part that fits inside the steering wheel, under the dashboard on the passenger’s side, or in the side of the seat or door panel. The module contains the airbag cushion and a metal canister, or inflator, which holds a chemical propellant that is ignited when there is a crash, rapidly creating gas needed to inflate the cushion.
Behind the scenes of an airbag cushion are crash sensors that signal a computer – the airbag control unit (also called an airbag control module or airbag electronic control unit) – when the vehicle is rapidly decelerating. The sensors are designed and calibrated to detect the difference between running over a pothole, which does not require deployment, and a collision that does. Other sensors on the vehicle provide information about braking, wheel speed, occupant locations, and other factors that determine how the airbags and seatbelts should respond. This includes whether a crash is severe enough to require the airbag to deploy faster and which airbags should deploy based on the location of the collision. The airbag control unit processes all of this data and instructs the airbag to deploy or suppresses deployment based on mathematical calculations. If the airbag control unit calculates that a deployment is needed, an electrical signal ignites the chemical propellant inside the airbag module and deployment is commanded within milliseconds. These components are connected via wiring and include malfunction indicators intended to illuminate a warning light if the airbag control unit detects a problem in the system.
Airbag system components are intended to function even in severe crashes. But various problems can prevent deployments when needed. For example, component parts may be located in areas that can be damaged in a crash preventing proper functioning, sensor calibrations can “drift” over time affecting how they determine when and if to signal deployment, and control units can exhibit design or manufacturing defects that fail to process when and if to properly deploy the airbags.
What Should You Do If Your Airbag Deploys?
Do not drive your vehicle until the airbags have been replaced. Replacement should be done at an authorized service center by a certified technician. Because of the high expense of replacing airbags – it can cost anywhere from $750 to $6,000 depending on which airbags need replacement – some owners may purchase used airbags from scrapyards or websites like eBay. This can be risky because the airbag may have been subject to a recall or have unseen damage. Finally, the National Highway Traffic Safety Administration has warned that some airbags sold through unauthorized dealers may be counterfeit airbags that do not meet safety standards and have failed in lab testing.