Airbag Impact Sensors

What are airbag impact sensors and where are they located?

Airbag impact sensors, also known as crash sensors, are important safety features for your vehicle. These sensors, located throughout your vehicle, detect a collision and trigger the airbags to go off. They are usually found at the front of the vehicle, behind the front fender, to detect a frontal impact, and in the side columns to detect a side impact. The exact number and location of airbag sensors you have will vary from one model to another, but those are the most frequently used locations. 

Understanding exactly how the impact sensors work may require a quick physics refresher but don’t worry, we’ll try to be brief, and we won’t test you on any of this. The purpose of your airbags is to counteract your inertia if your vehicle abruptly stops moving forward, like in a collision. Since you are not part of your car, you will continue moving forward at the same speed that the car had been going. An object in motion stays in motion unless acted upon by another force. That other force is provided by your airbags (as well as your seat belts). Your impact sensors are actually activated by the same inertia that you would experience in a collision. They contain an object that can move, like a roller or a ball, and something that holds that object (somewhat weakly) in place, like a spring or a magnet. If the car suddenly stops, the roller or ball will keep going forward and contact a switch, which tells a computer, the airbag control module, to deploy the airbag. The spring or magnet holds the roller or ball back so that it doesn’t activate the switch in normal deceleration situations – like when you hit your brakes hard. These sensors are calibrated to set off the airbag in a crash that’s roughly equivalent to hitting a brick wall at ten miles per hour or faster. In order to keep you safe, the sensors need to strike a balance where they set the airbags off when they’re needed and don’t set them off when it’s not needed. 

How do I know if my airbag impact sensors need to be replaced?

When you start your car, the airbag control module will test to make sure the airbag sensor circuits are functioning correctly. As it does this check, you will see that the airbag warning light on your dashboard light up. This light shows an image of a driver with a deployed airbag. If the light stays on after starting, this is your warning that something is wrong with a component in the airbag system. If the light flashes, you can read the pattern of flashes as a two-digit code. For example, if the light flashes twice, pauses, and then flashes three times, you can read that as code 23. You can then find out what that code means for your particular vehicle. A mechanic with a diagnostic scan tool may also be able to pinpoint the exact cause of your problem. It is not advisable to try testing your airbag circuits with a multimeter or probe, since you could cause the airbag to fire unintentionally and then you’ll have much bigger problems than a faulty sensor. 

If you do have a collision, and the airbags go off, the sensors may suffer internal damage, which will keep them from working properly in the future. Many automakers recommend replacing your airbag sensors after any collision in which your airbags go off. Other manufacturers state that their sensors will reset themselves after a collision and need not be replaced. You should check your automaker’s recommendations, although you may choose to replace the sensors anyway just to be safe. 

If there is something wrong with your airbag system, it is important to get the problem fixed as quickly as possible, for safety’s sake. 

Can I replace airbag sensors myself?

Although you will need to exercise certain cautions, you can replace your own crash sensors. The most important precaution you need to take is to depower the airbag system. You should disconnect the car’s battery and then leave your headlight switch on to dissipate any remaining charge in your vehicle systems. Then you should wait around ten minutes longer. The airbag sensor is actually designed to be able to activate for a short time after losing power. This is so that the airbags will still work in a collision where the vehicle loses power. Once you are confident that the airbags will not activate, you can access the sensor, disconnect it, and install the new one. Depending on the exact locations of your sensors, and which one you need to replace, you may need to remove your front fender or your door column trim, or other body panels. 

Need an airbag sensor replacement?

While the airbag itself is obviously critical, the success of a vehicle’s airbag system relies upon the crash sensors. The first step in deploying the airbag is for the system to actually realize that a crash has occurred, and this is accomplished by these sensors, so their importance cannot be overstated. If you need an airbag sensor replacement to get your system back in working order again, you have come to the right place. 1A Auto carries a large selection of airbag sensors for many makes and models, and at great prices.

At 1A Auto, we make shopping for replacement airbag sensors for your car, truck, SUV, or van easy—we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our airbag crash sensors, warranty, compatibility or to purchase, or you can buy online.