Seat Belt MOT Failure: The Webbing, Buckle and Retractor Rules

Seat belts are one of the few MOT items you can check properly yourself, which is good, because every belt fitted to the car is inspected. Not just the driver’s, and not just the front.

In short: Every seat belt fitted is checked. A missing statutory belt, damaged or stretched webbing, a buckle that does not latch or release properly, or a retractor that does not wind the belt back in are all Major defects under 7.1.2. A loose belt anchorage is also Major under 7.1.1 (b).

What the Tester Checks

Section 7.1.2 lists five defects, every one of them Major:

• A statutory seat belt missing (a).
• Webbing or a flexible stalk significantly stretched, damaged or weakened (b).
• A belt not functioning as intended, or of the wrong type (c).
• A buckle missing, damaged or not functioning as intended (d).
• A retractor not functioning as intended (e).

For the webbing, the manual is specific. A cut of more than 2mm on either edge is a deficiency, because the edges carry the most load. Away from the edges, damage has to be obviously more than 4mm. Any cut at all on a child seat’s own harness counts. Fluffing, fraying and signs of overstretching are all looked at.

The buckle test is simple: fasten it, try to pull it apart, then press the release while pulling and make sure it lets go. For retracting belts, the tester checks the slack winds back in with the belt fastened, the seat empty and the seat slid fully back. Folding rear seats are lifted to get at the belts underneath, unless that would need tools.

The Parts You Cannot See

Belts are only as strong as what they are bolted to. Under 7.1.1 a loose anchorage is a Major defect, and the area within 30cm of each anchorage is a prescribed area: corrosion that significantly weakens it is Major, and an anchorage likely to come away in a crash is Dangerous. Pre-tensioners and load limiters fitted as original equipment are checked too: one that is obviously missing or has already gone off is a Major defect (7.1.3 and 7.1.4).

Common Reasons Belts Fail

• Webbing chewed by a dog, or cut by a sharp seat runner or a door that closed on it.
• A retractor that has got lazy, leaving the belt hanging slack.
• Rear buckles full of crumbs, coins or spilt drink, so they will not latch or release cleanly.
• A rear buckle hidden under a fixed child seat: in that case the tester checks as much as they can and adds an advisory that the buckle could not be checked.

If a child seat is involved, our post on whether a child seat can fail your MOT is worth a read.

The Two-Minute Check Before Your Test

Pull each belt all the way out and look along both edges. Let it wind back in. Fasten each buckle, tug it, then release it. Give the belt a sharp yank to make sure it locks. That covers most of what the tester will do.

Booked In Soon?

Found a belt that will not retract or a buckle that sticks? Any of our 12 branches across Nottinghamshire can take a look, and with over 20,000 MOT tests a year behind us there is not much we have not seen. We will show you what we found, explain it in plain English and confirm the price before any work starts. Book an MOT online when you are ready.

A frayed, cut edge on a seat belt. Edge damage over 2mm is a deficiency, because the edges carry the most load.

Webbing frayed where it runs through the pillar guide. Every belt is pulled out and checked along both edges.

Frequently asked questions

Do all seat belts have to work to pass an MOT?

Yes. Every seat belt fitted is inspected, front and rear, and each must latch, release and retract properly. The only exceptions in the manual are a belt with no matching seat, or a buckle or stalk with no matching belt.

Do they check seat belts on an MOT?

Yes, under section 7.1: the anchorages and the structure around them, the webbing, buckles and retractors, plus pre-tensioners and load limiters where they were fitted as original equipment.

How big a cut in a seat belt fails the MOT?

More than 2mm on either edge of the webbing, or damage obviously over 4mm away from the edges. Any cut on a child seat’s own harness is a deficiency.

Can a seat belt warning light fail the MOT?

The MOT manual has no defect for a seat belt reminder chime or light. The airbag (SRS) warning light is different: if it shows a fault in the system, which includes the belt pre-tensioners on most cars, that is a Major defect under 7.1.6. A pre-tensioner that has obviously already gone off is also Major, under 7.1.4.

How much does it cost to fix a seat belt fault?

It depends on the underlying cause and the vehicle, which is why we always inspect first. Once we can see exactly what is needed we will explain it in plain English and confirm the price with you before any work starts.