Airbag Failure: Reasons, Risks and Safety Precautions

Modern airbag systems are incredibly reliable, so when they fail it’s usually because something went wrong elsewhere: damaged wiring after a previous repair, a faulty crash sensor, a worn clock spring in the steering wheel or water getting into the airbag control module under the dashboard or carpet.

Any of these can stop the airbag from deploying in a crash or, in extreme cases, trigger it when you’re not expecting it. If the former happens, you have very little protection in a collision. And if the airbag suddenly and violently deploys, it’ll block your view of the road and potentially injure you.

Because of that, you should treat any airbag warning light or obvious fault as extremely urgent. The only safe move is to get the fault code read, understand what’s actually failed and have a qualified technician handle the repair.

This guide explains what airbag failure really means, the main reasons it happens, the warning signs to look for and what your repair options are in the UK.

What is an airbag system?

An airbag system, officially called the supplementary restraint system (SRS), is a network of components designed to protect you in a serious collision. It includes crash sensors, wiring looms, the airbag control unit (ACU), inflators and the nylon bags themselves, which are positioned in the steering wheel, dashboard, seats and pillars.

When a collision occurs, the sensors detect the impact almost instantly and feed that information to the ACU. The ACU decides which airbags need to deploy and triggers an electrical charge inside the inflator. That charge rapidly creates harmless nitrogen gas, which fills the nylon bag and forces it out of its housing to cushion you before you hit hard surfaces.

After inflation, the bag deflates through small vents, allowing your head to move and your chest to breathe naturally. Controlled deflation is crucial because it prevents you from bouncing off a rigid surface and reduces the risk of chest compression, breathing difficulty or secondary injury.

The entire sequence of detection, inflation and the start of deflation happens in under 50 milliseconds. If anything in that chain is even slightly out of sync, the SRS can’t protect you properly, which is why tiny faults in wiring, sensors or the ACU matter far more than they seem.

What are the reasons for the airbag light to come on?

Most of the time the airbag light turns on, it’s because of faulty crash sensors, a worn-out clock spring in the steering wheel or damaged wiring that interrupts communication between the system’s components.

Other triggers still matter, though. It could also be due to a faulty airbag control module or an internal system error, loose connection under the seat, faulty seatbelt buckle sensor, or even a passenger airbag that was manually switched off (though not all cars have this feature).

In every case, the light means the system can’t guarantee proper deployment.

• Faulty or damaged sensors: Your car uses impact sensors to detect the exact moment airbag deployment is needed. Those sensors are constantly monitoring changes in speed and force and sending that information to the control module. If a sensor is worn out, damaged in a collision or simply fails with age, the system knows it can’t trust the data so it switches the warning light on. Even a minor knock or pothole hit could be enough to disturb an already-weak sensor.
• Wiring issues and corrosion: When wiring gets frayed or corroded, it interrupts the electrical communication needed to transmit data and trigger the airbag in an accident. This happens most often beneath the seats and along the steering column. When it does, the system immediately flags the problem by illuminating the airbag light. If you don’t have this fixed, it’ll prevent the airbags from firing in a crash or, far less often, send a false deployment signal.
• Damaged clock spring: The clock spring is a coiled ribbon of wiring inside the steering wheel that maintains the electrical link to the driver’s airbag as you turn the wheel. When it wears out or snaps, the airbag loses that connection. You’ll notice the warning light flicking on when you steer sharply, because the turning motion of the steering wheel twists the broken part of the coil. 
• Seatbelt issues: A faulty seatbelt buckle sensor or loose connector under the seat can confuse the airbag system and trigger the warning light, as can an improperly fastened seatbelt. Since the seatbelt locks to restrain you on impact, the seatbelt sensors help the airbag system determine how forcefully the airbags inflate, and in some cases whether they should deploy at all.
• Airbag switch set to ‘off’: Some cars let you manually disable the passenger airbag, usually for child seat safety. If that switch is set to “off”, the system might illuminate the airbag warning light or show a separate ‘passenger airbag’ indicator. This is obviously intentional (in order to protect the child), but it still means the car is telling you the system won’t fire that airbag in a crash. Drivers often forget they changed the switch after carrying a baby seat.
• Previous vehicle accidents: After a crash, components may be misaligned or slightly damaged, or the mechanic might not have installed them properly. Even a light bump that didn’t set off the airbags might still disturb the sensors, wiring or mounting brackets inside the airbag system. Either way, the result is a system that fails its self-check every time you start the engine, which triggers the warning light. This is especially common when repairs were done without replacing all the airbag-related hardware.
• Airbag module failure: The airbag control module reads sensor data, decides which airbags to fire and stores crash information. If the module develops an internal fault, gets water damaged, or wasn’t reset properly after a previous collision, it won’t be able to guarantee safe deployment, making your car extremely dangerous to drive. When that happens, the light activates immediately and the car may disable parts of the system until you repair or replace the module.

What are the signs of airbag failure?

You’ll always see the airbag warning light if your airbag system is failing, but besides that, airbag problems don’t really show themselves dramatically. The main two signs are strange noises from inside the dash or steering wheel and issues with other safety systems inside the car.

Catching these signs early matters because the only other warning sign is an airbag that doesn’t go off. And by that point, your safety in the event of a serious accident is severely compromised.

• Airbag warning light: When you switch the ignition on, the light should appear briefly, then turn off with all the others once the system completes its checks. If it stays on, flashes or comes on again while driving, the airbag control module has detected a fault somewhere in the loop. Because the car might disable part of the system until the fault is fixed, you should get a diagnostic scan as soon as the light appears.
• Unusual airbag deployment sounds: Airbags make a loud, sharp bang when they deploy – that’s normal. What isn’t normal is hearing clicking, buzzing or rattling noises from the airbag areas without a crash. Those sounds can point to electrical faults, a damaged inflator or wiring arcing behind the dashboard or steering wheel. They’re rare, but a deteriorating inflator or a short circuit puts you at tremendous risk if you’re in an accident, so you should stop driving and get the system looked at as soon as possible.
• Delayed or non-deployment: The scariest sign of airbag failure is when the airbag deploys late or not at all in an impact. As mentioned earlier, failing sensors, wiring and airbag modules will delay or cut off the signal that tells the airbags to fire. Even a split-second delay reduces your protection significantly. If you’ve been in a crash where the airbags should have deployed but didn’t, you need a full system inspection before the vehicle goes back on the road.
• Issues with seatbelts or other safety systems: Seatbelts and airbags work together, so problems with one occasionally affect the other. If your seatbelt isn’t locking properly or the sensors aren’t working, it can interfere with how the airbags decide when (and how forcefully) to deploy. So if you notice seatbelt problems or strange behaviour from the seatbelt warning light, don’t treat it as just a seatbelt system fault. Because it could potentially be a sign of a wider airbag system fault that needs immediate attention.

What are the risks of airbag failure?

Since airbags work with other parts of your vehicle to absorb force and control your movement in a crash, your safety and life are at risk when they malfunction. If they fail to deploy or do so with the wrong amount of force, a moderate accident could turn severe or a severe accident could turn deadly.

And something most drivers don’t consider: it’ll also affect your insurance claim and the liability you face after an accident.

• Increased injury after accidents: Without a functioning airbag, the impact on your head, chest and neck will be far greater. The airbag’s job is to slow your movement and stop you from striking the steering wheel and side structures of the car. When it doesn’t deploy, the force transfers directly to your body. Passengers face the exact same risk, especially in head-on and T-bone collisions. Even at moderate speeds, the absence of an airbag can turn a survivable crash into a catastrophic one.
• Risk of non-deployment in a collision: If the system isn’t able to detect the crash properly, the airbags simply never receive the signal to fire. That delay or total failure significantly increases injury risk because the seatbelt is left to handle forces it wasn’t designed to manage alone. The good news is that regular maintenance, prompt diagnosis of warning lights, and addressing wiring or sensor faults early can dramatically reduce this risk.
• Secondary injuries from faulty airbags: In high-impact crashes, a mis-timed or overly forceful deployment can worsen injuries instead of preventing them. You might also see burns or abrasions from the fabric, bruising from excessive force or minor cuts from torn components during deployment. More serious is an airbag that deploys unexpectedly (for example, while manoeuvring at low speed), which can block your vision and startle you, potentially causing an accident.
• Legal implications of airbag malfunctions: If your airbag light is on and you ignore it, insurers will try to argue you haven’t kept the vehicle in a roadworthy condition (it’s considered a ‘dangerous’ defect, which is illegal to drive with under any circumstances). If it doesn’t void your policy altogether, it’ll certainly affect payouts, liability decisions and potentially whether you’re considered ‘at fault’ after the accident. And if you have passengers who sustain injuries, you’d also be held personally responsible for them. This is why keeping the system fully functional and addressing the issue ASAP isn’t just good safety practice; it protects you legally and ensures your insurance remains valid.

How can I prevent airbag failures?

Airbags don’t need a whole lot of day-to-day attention, but they do rely on the rest of the car being in good health. Most failures happen because you’ve ignored the wiring, sensors or a switch for too long. A bit of routine care, and avoiding the wrong modifications, goes a long way towards keeping your airbag system dependable.

• Regular vehicle inspections: A mechanic will be able to pinpoint things like damaged wiring, loose connectors, outdated software and sensors that aren’t responding correctly. Modern diagnostics make it easy: a quick scan pulls fault codes even if there are no outward symptoms yet. So making system checks part of your usual service schedule will stop any minor issue you have from turning into a full airbag failure.
• Keeping sensors and wiring in good condition: Sensors and wiring do all the heavy lifting, and they’re also the most vulnerable to wear and corrosion. You can’t realistically check them all yourself (many are hidden), but you can avoid situations that cause damage that leads to airbag failure, like forcing seats back against wiring looms and ignoring water leaks in the cabin.
• Avoiding aftermarket modifications: Aftermarket steering wheels and seat changes easily disrupt the airbags’ wiring and confuse the control module. And if you have the inflators or airbags replaced with a knock-off version, it’s especially risky because they might deploy improperly or trigger fault codes. The only safe approach is to stick with manufacturer-approved parts and avoid modifications that interfere with sensors, wiring harnesses and the airbag housing.
• Ensuring proper seatbelt use: Seatbelts and airbags work as a team, so if the belt isn’t properly fastened or if the buckle sensor isn’t working, the car might adjust the airbag deployment force or decide not to deploy at all. Simple habits help: make sure belts latch cleanly, avoid twisting the straps and don’t ignore warning chimes. And if a belt feels loose, get it checked because it could cause an airbag system issue too.
• Promptly addressing airbag warning lights: The airbag light is never something to ‘monitor for a few days and see if it goes away’. Once it’s on, the system has already disabled one or more airbags. Ignoring it leaves you unprotected in a crash. The right move is to book a diagnostic scan to get the fault code read. From there, follow through on the repair. Most issues are sensor- or wiring-related, so they’re relatively cheap to fix (especially compared to the increased liability you face if there’s an accident).

When should you repair or replace your airbags?

Airbag decisions usually come down to three things: the type of fault, the condition of the car, and the repair cost. Some issues, like with the sensors and wiring, are quick fixes. Others, like a damaged inflator or housing, require full component replacement. And full replacement can be surprisingly expensive, so sometimes it’s simply not worth the money.

When to repair your airbags

Repairs are ideal when the airbag light is on due to an electrical or communication fault, but never for physical airbag damage. Common repairable issues include:

• Faulty or worn crash sensors
• A damaged or worn clock spring
• Frayed or corroded wiring
• Loose connectors under seats or in the steering column

A control module that needs a reset rather than full replacement
Repairing airbag components is far cheaper than fitting new airbags, plus you keep the original factory-installed safety components. And it’s fast – most electrical issues can be resolved quickly with diagnostics and targeted fixes.

When to replace your airbags

Airbag replacement is an absolute requirement anytime the airbag system has been physically compromised. Clear signs you need new airbags or components:

• Any airbag has deployed in an accident
• The inflator or housing is damaged
• The airbag control module has failed and cannot be reset
• Crash data is locked in the module and cannot be cleared
• Sensors or brackets have been crushed or distorted in an impact

A deployed or damaged airbag cannot be reused, and replacement is the only way to restore full crash protection to factory standards. Insurers also expect full system replacement after deployment in order to keep the vehicle roadworthy.
When scrapping a car with airbag issues is the better option

Scrapping your car is the better option when:

• The car is old and low-value
• Multiple airbags deployed in a crash
• The repair estimate exceeds 50% of the car’s market value
• The airbag module, sensors, wiring looms and inflators all need replacing

Keep in mind that when you do scrap your car, it will affect what you’re paid for the car. Faulty airbags will slightly reduce the payout because none of the airbags or related systems can be pulled out and resold. Scrapyards also have to safely deactivate or remove airbags during depollution, which adds handling steps.

How much does it cost to repair or replace the airbags?

To repair or replace the airbags and the system’s components, you’re looking at a few different price ranges: sensors are £60 to £120, front airbags cost £200 to £350 (up to £500+ on high-end cars), seatbelts cost £150 to £300 and airbag control units cost £200 to £700. Some services can also reset certain modules for as little as £30 to £50 instead of replacing them.

Airbag repair and replacement costs (UK, 2025)

Here’s a breakdown of everything you might need to have done:

Labour rates also swing wildly across the UK, which is why the same job can cost twice as much depending on your postcode. A small independent in the Midlands might charge £60 to £80 an hour, while a dealer in London will almost always push that figure between £120 to £140.