Will a Car Fail MOT with the Airbag Light On?
If your airbag warning light is on, it can raise an important question before your MOT: will my car fail the test? The airbag system, also known as the Supplemental Restraint System (SRS), is a critical safety feature that protects you in the event of a crash. In the UK, MOT testers must ensure all safety systems are working correctly. Since the airbag is part of the car’s safety restraint system, any fault indicated by the warning light will affect your MOT result. This guide explains what the airbag light means, whether it causes an MOT failure, and how much repairs typically cost in the UK.
What the Airbag Light Means
When you start the car, the airbag light should turn on for a few seconds and then go out. This short illumination is a normal self-check.
If the light stays on or flashes, it means the system has detected a problem. The issue could be caused by:
- A faulty seatbelt pretensioner sensor
- Loose wiring under the front seats
- A broken clock spring in the steering wheel
- A defective airbag module or crash sensor
- Low battery voltage or a recent power issue
When this light is illuminated, one or more airbags may not deploy correctly in an accident, which reduces overall protection for the driver and passengers.
Will a Car Fail an MOT with the Airbag Light On?
Yes, your car will fail the MOT if the airbag light is on.
The DVSA (Driver and Vehicle Standards Agency) states that an illuminated SRS light is classed as a major defect. The MOT tester must fail the car if:
- The light stays on after the system check
- The light does not illuminate at all when the ignition is turned on
- Any part of the airbag system appears to be missing, disconnected, or deliberately disabled
In other words, the airbag system must work correctly, and the light must operate as designed for your car to pass the MOT.
Common Causes of an Airbag Warning Light
| Cause | Description | Typical UK Repair Cost |
|---|---|---|
| Faulty Seatbelt Pretensioner | Broken connector or sensor fault | £150 – £300 |
| Steering Wheel Clock Spring | Worn or damaged wiring connection | £200 – £400 |
| Airbag Control Module Fault | Internal failure or software error | £300 – £800 |
| Loose Wiring Under Seat | Common due to seat movement | £60 – £150 |
| Low Battery Voltage | Weak battery causing fault code | £50 – £120 |
How to Fix the Airbag Light Before MOT
- Inspect the seat wiring under the front seats. Loose or corroded connections are very common.
- Use a diagnostic scanner to identify the fault code accurately.
- Repair or replace the faulty part, such as a sensor, module, or wiring harness.
- Clear the error codes using professional diagnostic equipment and verify that the light stays off.
Most garages can repair airbag issues within a few hours once the fault is identified.
Is It Safe to Drive with the Airbag Light On?
It is not safe to drive long-term with the airbag light on. While the car may still operate normally, the airbags may not deploy in a collision.
In some cases, a faulty SRS system can disable airbags completely or cause them to deploy incorrectly. This poses a real safety risk.
If both the airbag light and seatbelt light are illuminated, you should have the system checked immediately by a qualified technician.
How to Prevent Airbag Light Problems
- Avoid moving seats while the ignition is on.
- Keep battery voltage healthy; low power can trigger SRS faults.
- Service the airbag system according to the manufacturer’s schedule.
- Do not remove or replace seats without disconnecting the battery first.
- Address warning lights quickly to prevent further damage.
MOT and Pre-Purchase Inspection Advice
If you are buying a used car and notice that the airbag light stays on, this means the SRS system is not functioning properly. It may pass a basic drive test but will fail its MOT.
A CAREXAMER pre-purchase inspection can detect dashboard warning lights, wiring faults, and airbag-related issues before you buy the car.
If your car fails its MOT due to an airbag warning light, you must have the fault repaired and the car retested before you can legally drive it again.
Summary of Airbag Light Causes and Costs
| Problem | Effect | UK Repair Cost |
|---|---|---|
| Loose seat wiring | Intermittent airbag fault | £60 – £150 |
| Pretensioner sensor fault | Warning light stays on | £150 – £300 |
| Clock spring fault | Airbag disabled | £200 – £400 |
| Control module fault | Entire system failure | £300 – £800 |
| Battery voltage issue | False warning | £50 – £120 |
Conclusion
A car will fail its MOT if the airbag light is on, as it means a critical safety system is not working properly.
Although the car may still drive, it will not offer full protection in an accident.
Typical UK repair costs range from £50 for a simple wiring repair to about £800 for a full airbag module replacement, depending on the issue.
For safety and compliance, always have the airbag system repaired by a qualified professional. If you are buying a used car, a CAREXAMER inspection can highlight any airbag or electrical problems before you purchase.
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