A lit airbag warning light on your dashboard is not a false alarm you can ignore. This warning light indicates that your safety system is not functioning properly, which seriously reduces your protection in the event of a collision. Whether the cause is a faulty sensor, wiring issue or an internal fault in the module, it must always be identified and fixed. This article explains what you need to know about airbag and seat belt warnings. You will find out when action is required.
What the airbag warning light on your dashboard means
The airbag warning light usually appears as a red or amber symbol, sometimes shown with the letters “SRS” (Supplemental Restraint System). This light should only illuminate briefly when you start the car. If the light stays on continuously or flashes, it indicates a fault in the safety system.
The colour and behaviour of the light provide important information about the urgency. A red light requires immediate action and you should visit a workshop as soon as possible. An amber or yellow light should be checked within a short period of time, but is less urgent. In some makes, such as the Seat Toledo, a flashing light indicates that the airbag module may not be functioning correctly.
In addition to the light on the dashboard, seat belt warnings may also appear. These systems are directly connected to the airbag module and together form your main protection in a collision. Faults in these systems mean you may not be fully protected in an accident.
‘ Even if they still look fine on the outside, they may be damaged internally and no longer provide adequate protection. ’
Common causes of airbag system warnings
Flat or weak battery
A common cause is a flat or weak main battery. The airbag system has a backup battery that supplies power when the main battery fails. When your main battery runs flat, this backup battery is also drained. This automatically triggers the warning light. The solution is simple: fully charge the battery. Once the main battery is charged again, the backup battery also charges and the light should go out.
Problems with belt tensioners
Modern cars are equipped with belt tensioners that automatically tighten the seat belt in a frontal collision. These tensioners are directly connected to the SRS system and can cause faults when they fail or have already been triggered. A triggered belt tensioner cannot be repaired and must always be replaced.
After an accident in which belt tensioners have been triggered, all seat belts that were in use must be completely replaced. Even if they still look fine on the outside, they may be damaged internally and no longer provide adequate protection.
Faulty crash sensors
Your car contains crash sensors that detect sudden deceleration. These sensors are connected to the computer system and give the signal to activate airbags in a collision. Worn or damaged sensors can cause false warnings. They can also mask real problems. Sensors are sometimes damaged in previous collisions. They may still continue to function afterwards but then provide unreliable signals.
Wiring and connectors
Damaged cables, loose connectors or corrosion can cause faults in the airbag system. This is especially a problem in older vehicles. Wiring there can wear out due to vibrations and temperature fluctuations. Moisture entering the airbag module after heavy rain or submersion can cause a short circuit and activate the warning light.
Internal faults in the airbag module
The SRS module itself can suffer an internal failure. This happens less often than other causes, but it is a serious problem that requires professional diagnosis. Common fault codes for module failures include B1015 (internal fault in airbag module), B1139 (fault in the airbag sensor unit) and B1620 (internal fault in the airbag module). With B1620 the module must be replaced.
How to diagnose an airbag system fault
Diagnosing airbag system problems requires specialised equipment. A professional OBD2 scanner can read fault codes from the system and provides more information about the exact cause of the problem. Many garages offer this service for a small fee or even free of charge with an inspection.
After reading the fault codes, the workshop can determine what repair is needed. This can range from replacing a clock spring (the component that maintains the electrical connection with the steering wheel) to repairing wiring or replacing crash sensors. In some cases, a reset and reprogramming of the SRS module is sufficient.
Airbags are sometimes deployed after a collision. In that case, simply replacing the airbags and belt tensioners is not enough. The airbag module must be reset and reprogrammed. This clears crash data and fault codes. Without this reset, the light will stay on, even after all damaged parts have been replaced.
Costs of airbag repair
The costs of airbag repair vary greatly depending on the cause of the problem. A simple reset or replacing wiring can cost a few hundred euros. Replacing crash sensors is usually between 200 and 500 euros per sensor, depending on make and model.
For more complex repairs, costs can quickly rise. Replacing a complete airbag module can cost 500 to 1,500 euros, including labour and reprogramming. Multiple airbags are sometimes deployed after a collision. The total cost of replacing airbags, belt tensioners and resetting the module can then run into several thousand euros.
Many of these costs are covered by fully comprehensive car insurance in the event of a collision. Always check your insurance policy to see what is reimbursed. If the defect occurs without a collision, the costs are usually subject to your excess or must be paid entirely by you.
‘ The costs of repair do not outweigh the risk you take by driving without working airbags. ’
Is it dangerous to drive with an airbag system fault
Technically, it is not illegal to drive with a defective airbag system. However, it is very unsafe. Your safety system does not provide protection in a collision, which means you are at much greater risk of serious injury in an impact. A non-functioning safety system also weakens your position in insurance claims after an accident.
Some car problems can be postponed temporarily. A defective airbag system, however, always requires prompt action. The costs of repair do not outweigh the risk you take by driving without working airbags. So arrange an appointment at an approved workshop as soon as possible to have the fault diagnosed and fixed.
Prevention and maintenance of the airbag system
Regular checks help to detect problems at an early stage. Pay attention to the behaviour of the airbag warning light every time you start the car. The light should come on briefly and then go out. If the light stays on or flashes, have it checked immediately.
Maintain your battery properly to prevent false warnings. A well-maintained battery ensures that the backup battery of the airbag system remains fully charged. Have your battery tested regularly. This is especially important before winter, when batteries are under extra strain.
Always go to an approved workshop for airbag system diagnosis and repair. This requires specialised knowledge and equipment that is not available in every garage. Make sure the technician has experience with SRS systems and electrical diagnostics. Keep all maintenance and repair invoices for your insurance and possible resale of the car.
Safety guidelines for the airbag system
Never try to replace parts of the airbag system yourself. After activation, belt tensioners are extremely dangerous to touch and may only be replaced by professionals. The airbag module contains sensitive sensors and requires specialised equipment to be reset.
Crash sensors should also only be checked or replaced by qualified technicians. Incorrectly adjusted sensors can cause airbags not to deploy when needed, or to deploy unexpectedly during normal driving. The latter is rare but can create dangerous situations.
If in doubt, always call in a professional. The airbag system is literally vital and deserves proper attention and expertise. Cutting costs on this repair is not a wise choice when it comes to your safety.
Do you have an airbag warning light illuminated on your dashboard? Then book an appointment immediately at an approved workshop for diagnosis and repair. Also check the Carnews website for other articles on safety systems, common car problems and maintenance tips for your make and model.
Frequently asked questions
The most common causes of an illuminated airbag warning light are problems with the (backup) battery, faulty or triggered belt tensioners, faults in crash sensors, damaged/loose wiring or an internal fault in the airbag module. You can start by checking and, if necessary, charging or replacing the main battery and all visible plugs and cables under the seats (without pulling roughly on them). For a targeted diagnosis, you can use an OBD2 scanner to read the SRS fault codes to see which component is causing the problem. Work on airbags, belt tensioners and the SRS module itself must then be left to a professional due to the safety risk.
By ignoring an airbag or seat belt warning, airbags and belt tensioners may not deploy or may deploy too late in an accident, increasing the risk of serious injury or death. A defect in sensors or wiring can also cause the system to respond unpredictably, for example by unintended airbag deployment while driving. In addition, previous damage or faults may go unnoticed, meaning you are driving without effective protection.
Yes, modifying or replacing seats, the steering wheel or other interior parts can cause airbag and belt warnings, because airbags, belt tensioners and sensors are often integrated in these components. Fault messages arise, for example, due to disconnected or damaged plugs, cables or sensors. Prevent this by disconnecting the battery before disassembly, carefully (dis)connecting plugs and cables, and preferably using original or type-approved parts. After the modification, always have the SRS system professionally checked and any fault codes cleared.
You cannot safely check yourself whether the airbags are still functioning if the warning light is on; always have the system read with an OBD2 scanner at a professional garage. Driving with an illuminated airbag light means that (parts of) the system may be deactivated and will not work in an accident. Costs vary greatly: for diagnosis and a simple reset you often pay a few tens of euros, but if parts such as sensors, belt tensioners or the airbag module need replacing, costs can run to several hundred euros or more. Always ask for a diagnosis first and a detailed quotation.
A constantly lit airbag light indicates a permanent fault in the airbag system, meaning that (parts of) the system may be deactivated; this is serious and must be checked as soon as possible. A flashing light often points to a (more serious) electronic or module fault, for example that the airbag module itself is not functioning properly. In practice, flashing usually means that control of the entire system is unreliable. Both are critical for safety, but a flashing light can indicate an even more fundamental fault in the control system than a continuously lit light.