Seatbelt and airbag MOT failures
Every seatbelt in the car is tested – front and rear – along with the airbags and other restraint systems where fitted.
Checked against the MOT inspection manual and GOV.UK guidance · Updated November 2026
Seatbelts
The tester checks each belt the vehicle is required to have:
- Webbing – cuts, fraying, stretching or damage
- Buckle – latches securely and releases when pressed
- Retractor – pulls the belt back in and locks when tugged sharply
- Anchorages – secure, and the structure within 30cm free of excessive corrosion
- Pretensioners and load limiters, where fitted – not obviously deployed or missing
Airbags and SRS
Since 2018 the MOT checks that airbags fitted as standard are present and not obviously defective, and that the supplementary restraint system (SRS) warning lamp works correctly. An airbag warning light that stays on, or doesn't come on at all at start-up, is a major defect.
Common failures
| Defect found | Usual category |
|---|---|
| Seatbelt webbing cut, frayed or damaged | Major |
| Buckle doesn't secure or release | Major |
| Retractor not retracting the belt | Major |
| Required seatbelt missing | Major |
| Seatbelt anchorage insecure or area excessively corroded | Major / Dangerous |
| Airbag missing or obviously defective | Major |
| SRS / airbag warning lamp on or not working | Major |
| Pretensioner or load limiter obviously deployed or missing | Major |
Airbag light on: common causes
- A failed connector under the front seats – often disturbed by moving the seats or cleaning
- A worn clock spring (the rotary connector behind the steering wheel) – very common
- A faulty seat occupancy sensor or seatbelt pretensioner
- A stored crash code after an accident, even if no airbag deployed
- A flat or weak battery triggering a fault that then needs clearing
Always get it diagnosed with a scan tool rather than simply clearing the light – the airbag system is safety-critical, and clearing codes without a repair just means the light comes back.
Repair costs
| Repair | Typical cost | DIY? |
|---|---|---|
| Airbag / SRS diagnostic scan | £40–£90 | Code reader with SRS capability |
| Under-seat connector repair | £40–£120 | Sometimes |
| Clock spring (steering wheel) | £80–£250 | Needs care – airbag removal |
| Seatbelt (complete, each) | £80–£300 | Often |
| Seatbelt pretensioner | £150–£400 | No |
| Airbag module replacement | £300–£1,000+ | No |
| Airbag control unit (reset or replace) | £80–£500 | No |
Typical UK independent garage prices including parts, labour and VAT, 2026. Main dealers and premium/4x4 vehicles cost more.