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Airbag Warning Light: What It’s for, Why It's On and How to Fix It

Stephen Fogel
July 25, 2018

The airbags in your car are a huge safety feature, and can save your life in a head-on crash. So, if something is wrong with the system that operates them, it’s a big deal. Thankfully, there’s a warning light that can clue you into such a problem.

The airbags are part of the supplemental restraint system (SRS), which also includes your seat belts and is designed to protect you in the event of a major frontal impact (and even in side impacts, on newer vehicles). 

The SRS warning light on the dashboard usually looks like a side view of a person sitting in a seat with a seat belt on, with a large circle (the airbag) in front of the person.

srs light

It will normally light up briefly each time you start your vehicle, and then go off. But if it stays on while you drive, or comes on while you’re driving, it indicates a problem with your airbags or some other part of the SRS. 

Let’s take a brief look at how your airbag system works, reasons the SRS light can come on, and why it’s OK to drive with the light on, but only if you get it fixed quickly.

How the airbag system works

Your SRS is a complex system with its own computer. This computer uses a network of sensors to detect impacts, deceleration, braking, whether the passenger seat is occupied, and other relevant data. If there’s a significant frontal impact, the computer will first send a signal to the seat belt pretensioners to tighten. This holds the occupants securely in their seats. 

Next, the computer sends a signal to the front airbag or airbags. An electrical impulse then ignites chemicals in the airbag inflator, which produces pressurized nitrogen gas that expands each airbag in about 50 milliseconds — about how long it takes you to blink. 

The airbag inflates and is there to cushion your head just as it’s moving forward. After absorbing the impact, the airbag rapidly deflates. Side impacts will trigger the side airbags, which can remain inflated for a longer period, in case the vehicle rolls over. 

So, it’s essential that your airbags and entire SRS be in perfect working order. The system even has a “black box” that records all the relevant accident-related data for the 20 seconds leading up to an impact.

Why the airbag light comes on

Because your SRS is such a complex system, there are many possible causes if your warning light comes on. Some may be obvious, while others may be hard to track down. Since you’re dealing with a key safety system here, any problem areas must be correctly diagnosed and corrected. They are best left to an experienced mechanic. 

The SRS computer can produce a trouble code that can aid in the diagnosis of the problem. Your mechanic will look for this early in the process to get to the source of the problem.

You may also want to check for any airbag or SRS-related recall notices on your vehicle. Some repairs may be covered under a recall or extended warranty.

Here are some common reasons why your airbag light comes on, and how your mechanic can fix it.

Your seat belt latch has a problem

Your SRS includes sensors that tell it whether the seat belts are fastened. A coin or other foreign object inside the seat belt buckle mechanism can trigger a fault that turns on the warning light.

Solution: Check inside the seat belt buckle for foreign objects and remove them. Have the SRS computer reset if necessary.

The passenger seat occupancy sensor is malfunctioning

Your front passenger seat contains a sensor that can tell whether someone is sitting there, and how much they weigh. This tells the SRS to fire the passenger airbag if an adult is in the seat. If this sensor is not working properly, it can cause the warning light to illuminate.

Solution: Check that the wiring connector is secure, the wiring is intact and the seat sensor is operational. Repair or replace any damaged components as necessary, and reset the computer as needed.

You have corrosion from water damage

If your vehicle has had interior water damage, there can be corrosion in SRS-related components. This will keep the system from working right, and the airbag light will come on.

Solution: Thoroughly inspect all parts of the system. Replace all corroded parts. Reset the SRS computer and verify that everything is in working order.

Your clock spring is bad

Your airbag clock spring is an electrical connector in your steering wheel. Its function is to maintain electrical contact between the driver’s airbag and the SRS computer as you turn the wheel back and forth. Over time, it can fail. If it does, the driver’s airbag will not deploy when the computer tells it to. The warning light will activate. 

Solution: The SRS computer will usually log a code that identifies this problem. Replace the clock spring and reset the computer.

Your SRS computer’s backup battery is drained

The SRS computer in your vehicle has a backup battery that enables it to retain its data, even when your vehicle’s power is cut off. A low or drained car battery can cause the SRS backup battery to get too low. When this happens, the warning light will come on.

Solution: Recharging or replacing the vehicle’s battery will usually allow the SRS backup battery to restore itself. The computer may need to be reset as well.

You had a previous accident that didn't trigger the airbags

If your vehicle was in an accident that triggered the crash sensors, but did not require the airbags to deploy, it can cause havoc with the SRS. This can result in an airbag warning light.

Solution: The SRS computer needs to be properly reset for normal operation.

You have a bad SRS computer

Electronic systems can fail, including your SRS computer. Factors such as age, heat, vibration and water damage can cause the computer to fail and turn on the warning light.

Solution: Replace the SRS computer and reset the system. Review your SRS warranty to see if some or all of the repair costs may be covered.

Get it diagnosed by a professional

Can I drive with the airbag light on?

Yes, but you need to get your car to a repair shop as soon as possible. 

If your airbag light is staying on, there’s a very real possibility that your airbags might not deploy in the event of an accident. This is a dangerous situation for you and your passengers.

There could also be further repercussions from your insurance company. The “black box” and the SRS computer will provide the information that the warning light was triggered and you did not fix the system before the accident occurred. Depending on the exact details of the accident, it might be grounds to deny you coverage.

 

Stephen Fogel

About the Author

Stephen has been an automotive enthusiast since childhood, owning some of his vehicles for as long as 40 years, and has raced open-wheel formula cars. He follows and writes about the global automotive industry, with an eye on the latest vehicle technologies.

1 User Comment

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By , January 03, 2011
RE: SRS warning light flashing; I had this problem intermittently for YEARS. The dealership had no answer and no log file was left. Several months ago the light flashed and kept flashing. I looked at the seat belt connectors, took off covers, wiggled wires, etc and it kept flashing until I attempted to take out the light bulb. I took the cover off the lower dash, above the pedals, and saw I could not access the bulb. There was some sort of sensor attached to the cover. Lo and behold, when I replaced the cover, the light had stopped flashing! I wish I knew why, but it did!

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