Understanding How Your Automotive Airbag Sensors Work

Posted by Artem Martynyuk on

Airbags might just be the single most important invention in automobile history. Very few innovations have saved as many lives as the humble airbags. In fact, airbags have been observed to reduce the chances of death during a crash by up to 42%. Considering how important airbags are, it’s quite surprising how little people actually know about them. This is why we thought it would be useful to put together an article that’ll help the everyday person understand how airbags work.

Instead of discussing airbags as a whole, it would be easier to focus on the main part that makes airbags tick: the airbag sensors. If this is something that you want to know more about, read on for a brief explainer on how automotive airbag sensors work.

Types of Crash Sensors

There are two types of crash sensors that you have to understand if you want to gain a better understanding of how airbags work. While these sensors are similar when it comes to the role they play in airbags, they do have key differences that alter how they work.

Crash sensors are usually positioned in the front of the vehicle, as this is where collisions normally occur. These sensors are fixed onto the engine and a similar sensor is located somewhere inside the passenger side of the vehicle. These sensors measure the intensity of a collision and will only deploy once the impact hits forces beyond a certain threshold. 

Mass type sensors feature a sensing mass. When the mass is forced forward into gold-plated contacts due to the strength of the impact, it will alert the airbag control unit that a collision is occurring so that the unit will trigger the airbags to deploy. This happens at near-instant speeds and will help prevent injury during a collision.

Similar to the mass type sensor, rolling type sensors also utilize a weighted mass that triggers the airbag control unit during a collision. Where the roller type sensors differ is that it consists of a weight connected to a coil spring component. With this type of sensor, it’s vital that the impact sensors and the safety sensors close off at the same time to ensure the deployment of the airbag.

While these are the most common types of sensors, technological innovations have paved the way for new sensors to be developed. There are now electronic crash sensors and sensor microsystems that are becoming more and more popular as they get implemented into newer vehicles.

The Airbag Control Unit

As we mentioned above, the sensors trigger the airbag control unit. The airbag control unit contains both the airbag and inflator assembly. The airbag control is vital to how airbags work as it is what commands the airbags to deploy once the sensor detects enough force. 

The way this works is simple. If the sensors detect enough force, they close and fire off an electrical current that is then transmitted to the airbag control unit. Once the current reaches the unit, it triggers an ignition between a pair of metal pins that inflate the airbags. This works similar to a small explosion as the pins activate a propellant, that’s made up of sodium azide, that burns and produces nitrogen gas.


We hope this article has helped give you a better understanding of how airbags work. While they may seem simple, airbags are made up of a multitude of different parts that work in unison to keep modern drivers (and passengers) safe from harm.

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