Airbag Warning Light Flashing – Causes and Risks

Is your airbag warning light flashing or staying on, even though the car drives perfectly normally? I hear this all the time at the workshop: "Kris, everything works fine. It's just that warning light annoying me. Can't we simply clear it?" We can clear the fault code, but that doesn't mean we've fixed the problem. And we're not talking about something minor that you can leave until your next service. We're talking about the airbags and seat belts that are supposed to protect you in a crash. If there's a fault in the system, some of that protection might not work at all. And that's something I'm not prepared to compromise on.

What does it mean when the airbag warning light flashes or stays on?

Every time you switch on the ignition, the airbag control module checks whether the system is working properly. It checks the airbags themselves, the seat belt pretensioners, the sensors and the electrical connections between them. If everything is fine, the warning light comes on briefly for the system check and then goes out. But if the control module detects a problem, the light may stay on or start flashing. That's the car's way of telling you it can't guarantee the system will work properly.

There's something important I want you to understand. An illuminated warning light doesn't necessarily mean all the airbags have stopped working, but it does mean there's a fault that needs investigating. You can't tell which part of the system is affected just by looking at the dashboard light. That's why I don't accept the explanation, "It's been on for ages, there's nothing wrong." There is a problem. You just don't know what it is yet.

What are the most common causes of an airbag warning light flashing?

There are several possible causes. Sometimes it's an electrical connection, sometimes a sensor or the airbag control module itself. There are also cases where the warning light is related to a previous accident. Here's what we check most often.

• Connectors under the front seats. These carry the electrical connections for the side airbags and seat belt pretensioners. Over time, the connectors can work loose or become corroded. Just one poor connection is enough to trigger the warning light.
• Clock spring behind the steering wheel. This is the coiled electrical connection that keeps the driver's airbag connected as you turn the steering wheel. It wears out over time and can eventually break. When that happens, the control module detects a fault in the airbag circuit.
• Passenger occupancy sensor. This is part of the system that detects whether someone is sitting in the passenger seat. If the sensor sends incorrect information or stops working, the control module may store a fault code and switch on the warning light.
• Low battery voltage. Not every airbag warning light means an airbag is faulty. Sometimes low voltage is enough to trigger a fault code. But! That needs to be confirmed with diagnostics, not simply assumed.
• Crash data stored in the airbag control module. After an accident, the control module may retain information about the impact. That's a completely different situation from a loose connector. The system needs to be checked and properly restored.

As you can see, the same warning light can mean several different things. So when someone tells you over the phone that it's definitely the cable under the seat, don't be too quick to believe them. Without diagnostics, that's just a guess. And when it comes to safety systems, guessing isn't good enough.

What do we check at the workshop when the warning light is on?

At Das Auto Service, we start with the airbag control module. It stores information about detected faults and helps us work out where to look. But reading the fault code is only the beginning. We then need to find out what's actually causing the problem.

1. First, we read the fault codes stored in the airbag control module. This tells us which part of the system has reported a problem.
2. Next, we inspect the connectors and wiring under the seats. We look for loose connections, corrosion and broken wires.
3. We check the electrical circuits and measure their resistance using the correct, safe procedures and suitable equipment. This helps us establish whether the fault is in a connection or one of the components.
4. If crash data has been recorded, we check the condition of the system. The control module is only replaced or restored according to the proper procedures, and we must be certain that the car's safety protection has been correctly restored.

Only after we've fixed the cause does it make sense to clear the stored fault code and check the system again. Otherwise, we've simply hidden the warning. Imagine your fire alarm goes off at home and someone decides to solve the problem by switching off the sound. That doesn't put out the fire, does it? It's exactly the same with your airbags.

Why is the airbag warning light so important when buying a used car?

Because on a used car, that warning light might tell you something the seller has conveniently forgotten to mention. If it's on, you need to find out why. And if it doesn't come on at all when you switch on the ignition, that's also a reason for a thorough inspection. Someone may have deliberately hidden the warning. And if the car has been involved in an accident, you need to know whether its safety systems have been properly restored.

I wrote about this years ago in my article on neglecting safety when buying a used car. Unfortunately, this isn't just a technical problem. It's also about people's attitude towards safety when someone would rather hide a fault than fix it. Then another person gets into that car with their family, without having the slightest idea.

Not every illuminated airbag warning light means the car has been in an accident. Let's be clear about that too. But every warning light like this deserves investigating, especially before you hand over your money for a used car. If you're wondering which other warnings you shouldn't ignore, have a read of Dashboard warning lights: which are dangerous and which can wait.

Tip from Kris Mladenov: When buying a used car, always check that the airbag warning light comes on when you switch on the ignition and then goes out. If it doesn't light up at all, don't take that as good news. Someone may have hidden the warning. Ask for a diagnostic check before making your decision.

I hope you've found this article useful! If you have, I'd be glad if you shared it with a friend who drives an Audi, VW, Škoda, SEAT, Cupra, Porsche, Bentley or Lamborghini. My mission is simple: when I know something, I want more people to know it too. Especially when we're talking about road safety. Sometimes sharing a piece of information can prevent a very serious mistake.

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Frequently asked questions

Why is my airbag warning light flashing?

Because the airbag control module has detected a fault in the airbag system. It could be caused by a cable, connector, sensor, seat belt pretensioner or stored crash data. The exact cause needs to be identified through diagnostics.

Is it dangerous to drive with the airbag warning light on?

Yes, because part of the safety system might not work properly in a crash. Don't put off getting it checked, and don't mistake clearing a fault code for a repair.

Could a connector under the seat be causing the problem?

Yes. A loose or corroded connector under a front seat can interrupt the electrical connection to the side airbag or seat belt pretensioner. This is one of the common causes of an illuminated airbag warning light.

Is it normal for the airbag warning light not to come on at all?

No. It should come on briefly when you switch on the ignition for the system check, then go out. If it doesn't light up at all, have it checked to make sure the warning hasn't been hidden.