Either the webbing itself is damaged — fraying, cuts, chemical damage — or the inertia reel isn't locking or retracting as it should. Both mean the belt won't restrain properly in an impact.
Wording as it commonly appears on an MOT certificate: “Seat belt webbing damaged or the retractor does not lock”.
What does it mean?
Either the webbing itself is damaged — fraying, cuts, chemical damage — or the inertia reel isn't locking or retracting as it should. Both mean the belt won't restrain properly in an impact.
How serious is it?
Usually recorded as: Major. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- Wear and fraying where the belt runs over a plastic guide
- A retractor mechanism gummed up with dirt or damaged by water ingress
- A belt trapped in the door repeatedly
- Corrosion inside the B-pillar affecting the reel
What a mechanic would check
Pull the full length of each belt out through my hands looking and feeling for damage, give it a sharp tug to check it locks, and watch it retract fully on its own. Then check the anchorage bolts and the surrounding metal for corrosion.
What might need replacing
- A replacement seat belt assembly
- Anchorage repair if the surrounding metal is corroded
Can you still drive it?
It's a failure and it's not one to compromise on. A belt that doesn't lock offers very little in a crash. Get it replaced before the car is used to carry anyone in that seat.
More seat belts and restraints failures · MOT failure decoder · Ask a mechanic about your certificate
This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.