Airbag Warning Light On? Causes, MOT Rules & How to Fix It in the UK
If your airbag warning light is on, your vehicle has potentially detected a fault within its Supplementary Restraint System (SRS).
The warning may be caused by something relatively straightforward, such as a poor electrical connection, or by a more significant issue involving an airbag, seat belt pretensioner, sensor or airbag control module.
If your vehicle has recently been involved in an accident, the airbag light may also be related to crash data stored within the airbag control module.
Whatever the cause, an illuminated airbag warning light should not simply be ignored.
In the UK, an SRS malfunction indicator lamp showing a system malfunction is categorised as a Major defect under the MOT inspection rules, meaning the vehicle will not pass its MOT with that defect present.
In this guide, we explain why your airbag light may be on, what the warning means, how SRS faults are diagnosed and when an airbag module reset may be required.
Quick Answer: Why Is My Airbag Warning Light On?
Your airbag warning light may be illuminated because the vehicle’s Supplementary Restraint System has detected a fault.
Common causes can include:
- Stored crash data following an accident
- A fault within the airbag control module
- A deployed airbag
- An activated seat belt pretensioner
- A damaged or faulty crash sensor
- Wiring or connector problems
- A seat occupancy sensor fault
- A steering wheel clock spring fault
- Low battery voltage or electrical issues
- A disconnected SRS component
The correct solution depends entirely on the underlying fault.
A professional diagnostic scan is usually the best starting point because it can identify fault codes stored within the SRS system.
Simply clearing the warning light without diagnosing and repairing the cause is not a proper solution.
What Does the Airbag Warning Light Mean?
The airbag warning light is part of your vehicle’s onboard safety monitoring system.
Depending on your vehicle, the dashboard warning may display:
- An airbag symbol
- The letters SRS
- A seated person with an airbag symbol
- An “Airbag Fault” message
- A “Restraint System Fault” message
- A “Supplemental Restraint System” warning
When you first switch on the ignition, it is normal for the airbag warning light to illuminate briefly while the vehicle performs system checks.
Under normal circumstances, the light should then go out.
If the warning light remains illuminated, comes on while driving or repeatedly returns after being cleared, the vehicle may have detected a fault that requires diagnosis.
What Is the SRS System?
SRS stands for Supplementary Restraint System.
The SRS works alongside the vehicle’s seat belts and can include several components designed to help protect occupants during a collision.
Depending on the vehicle, the system may include:
- Driver airbag
- Passenger airbag
- Side airbags
- Curtain airbags
- Knee airbags
- Seat belt pretensioners
- Impact sensors
- Seat occupancy sensors
- Seat position sensors
- Clock springs
- Wiring and connectors
- Airbag control module or SRS ECU
A fault involving one of these components may cause the SRS warning light to illuminate.
Because modern restraint systems are interconnected, diagnosing the correct cause is important before replacing or resetting any component.
What Are the Most Common Causes of an Airbag Warning Light?
There is no single reason why an airbag light comes on.
The following are some of the most common causes.
1. Crash Data Stored in the Airbag Module
If your vehicle has been involved in an accident, the airbag control module may have recorded information relating to the collision.
This is commonly referred to as airbag crash data.
Depending on the vehicle and the nature of the accident, stored crash data can remain within the SRS control module after damaged or deployed components have been replaced.
In some cases, the crash data cannot simply be removed using a standard diagnostic scanner.
A specialist airbag module reset service may be required to clear supported crash data from the module.
However, resetting the module does not repair other damaged components within the SRS system. Deployed airbags, activated pretensioners and other faults must be addressed separately.
2. Seat Belt Pretensioner Fault
Modern vehicles often use seat belt pretensioners as part of the SRS system.
During certain collisions, a pretensioner may activate to tighten the seat belt and help restrain the occupant.
Once activated, the pretensioner may need to be repaired or replaced as appropriate for the vehicle.
A fault involving a seat belt pretensioner may trigger the SRS warning light.
3. Loose or Damaged Wiring Under the Seat
Many vehicles have SRS wiring and electrical connectors beneath the front seats.
Moving a seat forwards and backwards can sometimes disturb wiring or connections.
If the system detects an abnormal electrical resistance or interrupted connection, an SRS fault may be recorded.
Because SRS systems contain pyrotechnic safety devices, owners should avoid probing, modifying or repairing airbag wiring without appropriate technical knowledge.
4. Faulty Seat Occupancy Sensor
Some vehicles use a passenger occupancy sensor to determine whether the passenger seat is occupied.
A fault involving this sensor or associated wiring may cause an airbag or restraint system warning.
The exact behaviour varies between vehicle manufacturers and models.
Professional diagnostics can help identify whether the occupancy detection system is responsible.
5. Steering Wheel Clock Spring Fault
The clock spring is an electrical connection located within the steering wheel assembly.
It allows electrical signals to pass between the steering wheel and the vehicle while the wheel is being turned.
Depending on the vehicle, a faulty clock spring may affect:
- Driver airbag
- Horn
- Steering wheel controls
- Cruise control buttons
If the driver’s airbag circuit is affected, the SRS warning light may illuminate.
6. Crash or Impact Sensor Fault
Vehicles can contain multiple impact sensors that provide information to the restraint system.
A damaged sensor, wiring fault or communication problem may cause the SRS system to register a fault.
This can sometimes occur following accident damage, water ingress or electrical issues.
7. Low Battery Voltage
A weak or discharged battery can sometimes contribute to warning lights and stored low-voltage fault codes.
If the airbag warning appeared after a flat battery, jump-start or battery replacement, diagnostic scanning may be required to determine whether a voltage-related code has been stored.
However, you should not assume that low battery voltage is automatically the cause.
The SRS fault codes should be read and diagnosed properly.
8. Airbag Control Module Fault
The airbag control module itself may develop an internal fault.
This is different from a module that simply contains stored crash data.
Depending on the type of failure, the module may require specialist assessment, repair or replacement.
Not every faulty module can be resolved through a crash data reset.
9. Previous Accident Repairs
If you have purchased a used vehicle and the airbag warning light appears, previous accident repairs could potentially be relevant.
The vehicle may have had:
- Airbags replaced
- Seat belt pretensioners replaced or repaired
- An airbag module replaced
- Crash data remaining in the original module
- Wiring repairs
- Replacement seats
- Previous SRS faults
A complete diagnostic scan can provide a useful starting point for investigating the history of the fault.
Is an Airbag Warning Light an MOT Failure in the UK?
Yes, if the SRS malfunction indicator lamp is indicating a system malfunction, this is categorised as a Major defect under the MOT inspection rules for cars and passenger vehicles.
This means the vehicle will not pass its MOT with that defect.
However, there is an important distinction.
A warning lamp that simply indicates the passenger airbag has been intentionally disabled is not regarded as an SRS system defect under the MOT inspection guidance.
The important factor is whether the SRS malfunction indicator lamp is indicating an actual system malfunction.
If your MOT is approaching and your airbag warning light is illuminated because of an SRS fault, the best approach is to have the vehicle professionally diagnosed before the test.
Do not rely on simply clearing the fault code immediately before an MOT.
If the underlying problem remains, the warning can return.
Can You Drive With the Airbag Warning Light On?
An illuminated airbag or SRS warning light indicates a potential fault within the vehicle’s restraint system.
The exact effect depends on the nature of the fault.
Because the system has detected a problem, you should not assume that all airbags, seat belt pretensioners and related safety components will operate as intended in another collision.
The appropriate action is to have the vehicle diagnosed by a suitably qualified professional as soon as practical.
SRS faults should be treated as safety-related issues rather than simply dashboard warning light problems.
How Do You Fix an Airbag Warning Light?
There is no universal “airbag light fix”.
The correct repair depends on the fault causing the warning.
A sensible diagnostic process typically involves the following steps.
Step 1: Read the SRS Fault Codes
A suitable diagnostic tool should be used to communicate with the vehicle’s airbag or SRS control system.
The stored diagnostic trouble codes can provide information about the circuit or component associated with the fault.
It is important to note that a fault code does not always mean the named component itself is defective.
For example, a code relating to an airbag circuit could potentially be caused by wiring, connectors or another electrical issue.
The diagnostic information should therefore be interpreted correctly.
Step 2: Identify the Underlying Problem
Once the codes have been read, the relevant components and circuits can be investigated.
This may involve checking:
- Airbags
- Seat belt pretensioners
- SRS sensors
- Wiring
- Electrical connectors
- Clock spring
- Occupancy sensors
- Airbag control module
If the vehicle has been involved in an accident, the repair history should also be considered.
Step 3: Repair or Replace Faulty Components
Any damaged or faulty components should be repaired or replaced as appropriate.
Because the SRS is a safety-critical system, repairs should follow appropriate technical procedures and vehicle manufacturer requirements.
Step 4: Reset Crash Data if Required
If the airbag control module contains stored crash data after an accident, a specialist module reset may be required.
The module can often be removed from the vehicle and sent to a specialist for assessment.
If the unit is supported and suitable for resetting, the relevant stored crash data may be cleared.
Step 5: Refit and Diagnose the Complete System
After repairs are completed and the module is refitted, the vehicle should be scanned again.
If all faults have been correctly resolved, the SRS warning light should operate normally.
Can You Reset an Airbag Warning Light With an OBD2 Scanner?
It depends on the fault and the diagnostic equipment being used.
Basic OBD2 code readers often focus primarily on engine-related diagnostic information and may not provide full access to the vehicle’s SRS system.
More advanced diagnostic equipment may be capable of reading and clearing certain SRS fault codes.
However, clearing a diagnostic trouble code is not the same as repairing the underlying fault.
If the problem remains, the code and warning light may return.
Additionally, stored crash data within an airbag control module may require specialist resetting procedures and may not be removable using conventional diagnostic equipment.
Will Disconnecting the Battery Reset the Airbag Light?
Disconnecting the vehicle battery is not a reliable method of repairing an airbag fault.
Diagnostic trouble codes or crash data may remain stored within the vehicle’s control systems even when battery power is disconnected.
More importantly, disconnecting the battery does not repair a faulty sensor, damaged wiring, activated pretensioner, deployed airbag or other physical SRS problem.
The correct approach is to diagnose the system and address the underlying cause.
Can I Reset the Airbag Light Myself?
While some diagnostic fault codes can potentially be cleared with suitable equipment, an airbag warning light should not simply be reset without identifying why it appeared.
The SRS includes safety-critical and potentially pyrotechnic components.
Incorrect handling can create a risk of injury or result in the restraint system not operating correctly.
If you do not have appropriate knowledge of automotive SRS systems, professional diagnosis is recommended.
Why Does My Airbag Light Keep Coming Back After I Reset It?
If your airbag light returns after the fault code has been cleared, the underlying problem may still be present.
For example, the vehicle could have:
- A damaged electrical connection
- Faulty wiring
- A defective sensor
- An activated pretensioner
- A clock spring fault
- A faulty airbag component
- An airbag control module problem
- Stored crash data
Clearing a code only removes the diagnostic record where the system allows it. It does not physically repair the cause.
When the vehicle detects the problem again, the warning light may return.
Why Is My Airbag Light Still On After Replacing the Airbags?
Replacing deployed airbags does not necessarily complete an SRS repair after an accident.
Other components may also have been affected.
Depending on the vehicle and collision, these could include:
- Seat belt pretensioners
- Crash sensors
- Airbag control module
- SRS wiring
- Other restraint components
The airbag control module may also contain stored crash data.
If the module is suitable, a professional airbag crash data reset may be required before the complete system can return to normal operation.
The vehicle should be professionally diagnosed to identify all remaining faults.
Do I Need an Airbag Module Reset?
You may require an airbag module reset if your vehicle has been involved in an accident and the SRS control module contains stored crash data.
Signs that further investigation may be required include:
- The airbag warning light remains on after accident repairs
- Diagnostic equipment reports crash or deployment data
- Airbags have previously deployed
- Seat belt pretensioners activated during a collision
- The SRS module will not clear using standard diagnostic procedures
However, not every airbag warning light means the module needs resetting.
If your vehicle has never been involved in an accident, another SRS component may be responsible.
A diagnostic scan should usually be performed before assuming the airbag module requires a crash data reset.
Airbag Warning Light After an Accident? Reset My Airbag Can Help
If your airbag warning light appeared following an accident, the vehicle’s SRS control module may contain stored crash data.
Reset My Airbag provides specialist airbag module reset services for customers across the UK.
Our service can help private vehicle owners, garages, mechanics, bodyshops and accident repair centres that need a supported SRS module assessed for crash data resetting.
Depending on the module, you may be able to send your original airbag control unit to us for specialist assessment and reset.
Once returned and correctly refitted, the complete vehicle SRS system should be diagnosed to ensure that any remaining faults have also been addressed.
Need help with an airbag module containing crash data?
Contact Reset My Airbag with:
- Vehicle make
- Vehicle model
- Year of manufacture
- Airbag module part number
- Details of the accident or deployment
- Diagnostic fault codes, if available
We can then help determine whether your module is suitable for our airbag reset service.
Frequently Asked Questions
Why has my airbag warning light suddenly come on?
An airbag warning light can appear because the SRS system has detected a fault. Possible causes include wiring or connector problems, faulty sensors, seat belt pretensioner faults, clock spring problems, low-voltage events or issues with the airbag control module. A diagnostic scan is the best starting point.
Will an airbag warning light fail an MOT?
If the SRS malfunction indicator lamp indicates a system malfunction, it is categorised as a Major defect under the MOT inspection rules for cars and passenger vehicles. A passenger airbag lamp indicating that the passenger airbag has simply been disabled is treated differently.
How do I get my airbag warning light to turn off?
The underlying SRS fault should first be identified using appropriate diagnostic equipment. Once the cause has been correctly repaired, fault codes can be cleared where appropriate. If crash data is stored within the airbag control module, specialist resetting may be required.
Can I clear an airbag light with an OBD2 scanner?
Some advanced diagnostic scanners can access SRS systems and clear certain fault codes. Basic OBD2 readers may not support the airbag system. Stored crash data may also require specialist equipment rather than a conventional diagnostic scanner.
Will disconnecting the battery clear an airbag light?
Disconnecting the battery is not a reliable way to fix an SRS warning light. Stored faults or crash data may remain, and disconnecting the battery does not repair the underlying problem.
Can a low battery cause the airbag light to come on?
Low voltage may contribute to certain stored diagnostic faults in some vehicles. However, the system should be scanned to identify the actual fault rather than assuming the battery is responsible.
Why is my airbag light on after an accident?
The SRS system may have detected deployed or activated restraint components, damaged sensors, wiring problems or stored crash data within the airbag control module. A complete diagnostic assessment is recommended.
Can an airbag module be reset after an accident?
Many airbag control modules can potentially be professionally reset after an accident if the module is supported, serviceable and suitable for the procedure. However, a module reset does not repair deployed airbags or other damaged SRS components.
Is it safe to ignore an airbag warning light?
An illuminated SRS warning light indicates a potential fault within a safety-related system. You should not assume the restraint system will operate normally while a fault is present. Professional diagnosis is recommended.
Final Answer: What Should You Do if Your Airbag Warning Light Is On?
If your airbag warning light is on, the first step is to identify why.
Do not simply clear the warning and assume the problem has been fixed.
Have the SRS system scanned with suitable diagnostic equipment, identify the underlying fault and repair or replace affected components as required.
If the warning appeared following an accident, the airbag control module may contain stored crash data and could require a specialist reset.
For UK drivers, it is also important to remember that an SRS malfunction indicator lamp indicating a system malfunction is categorised as a Major MOT defect.
If you believe your airbag control module requires a crash data reset, contact Reset My Airbag with your vehicle and module details to find out whether your unit is supported.