Will my seat belts fail my MOT?

Wednesday 9th September 2026

Seat belts are often overlooked when preparing for your MOT, despite being a vital safety feature. Faulty or damaged seat belts can result in an MOT failure. Our guide explains what to look out for when preparing for your MOT.

Reasons for seat belt failure

Most seat belt faults are considered a major or dangerous defect during your MOT, resulting in an automatic failure. Some common faults include:

Cuts: Any cut larger than 2 mm on the edge of the seatbelt or 4 mm on the interior strap will cause a failure.
Fraying or fluffing: Can indicate the strap may be structurally weak, resulting in an MOT failure.
Strap functionality: The seat belt must pull out smoothly, lock when pulled sharply and completely retract on its own.
Buckle functionality: The buckle must click and latch securely into the clip, and release cleanly when the button is pressed.
Warning lights: The dashboard includes an SRS (airbag/seat belt) warning light, if this illuminates and stays on, it is an immediate failure.
Child seats: If a seat belt can’t be accessed due to a child seat, the MOT tester can refuse to test the car, or in some cases, even issue a failure.

What to check before your MOT

Most seat belt issues can be easily avoided before your MOT test. Follow this simple check list before taking your car for testing.

Keep access clear: Ensure all child car seats and heavy luggage are removed from the vehicle.
Check the functionality: Click all the seat belts and give them a good tug to make sure they’re working as they should.
Unclick the belts: Make sure all belts are free and not trapped underneath folded seats.

How to fix a seat belt

Many seat belt issues can be fixed easily before your MOT. Follow these tips to understand when to repair and when to replace.

Seat belt won’t retract

If your seat belt won’t retract, it usually just needs a good clean.

Pull all the webbing out until the belt is fully extended
Use a peg or clamp to stop the strap from fully retracting
Wash the webbing with a mix of warm water and washing up liquid and a microfibre cloth
Wipe the D ring where the belt slides through to remove any oils and grit
Allow the belt to fully dry before releasing it

Seat belt won’t click

If your seat belt won’t click into place, it is usually caused by dirt and debris blocking up the plastic housing or sticky substances inside the mechanism.

Check inside the socket with a torch, as small objects can easily get caught and block up the buckle slot. Remove any pet hair, crumbs or toys with a pair of tweezers or canned air.
If the seat belt still won’t latch, flush the mechanism carefully with a lubricant like WD-40 ensuring it doesn’t get too wet.

When a seat belt needs replacing

Belts with rips, tears and fraying will always need replacing as patching is not a safe enough solution. Mechanical faults with your retractor spring, or a cracked, damaged housing that compromises the seat belt’s safety will also need a complete replacement too.