What does 5.1.1 mean on an MOT certificate?

It refers to sub-section 5.1.1 of the MOT inspection manual, "Axles", within section 5, axles, wheels, tyres and suspension. The letter or letters after it — (a), (b)(i) and so on — identify the specific defect from the 5 listed here. 3 of them are graded Dangerous, 2 Major and 0 Minor.

Which axles defect is recorded most often?

"An axle insecure or with loose fixing bolts" (5.1.1 (b)(i)), recorded about 0.0 times per 100 failed MOT tests nationally.

Does a Minor defect fail the MOT?

No. a defect with no significant effect on safety or the environment. Recorded on the certificate; the vehicle passes. Major and Dangerous defects fail. A Dangerous defect also means the car must not be driven until it is repaired.

Section 5 · Axles, wheels, tyres and suspension

5.1.1 Axles

Manual indexed 3 September 2026

Quick answer

Sub-section 5.1.1 of the MOT inspection manual covers axles and lists 5 defects, 3 of them Dangerous. A reference like "(5.1.1 (a))" on a certificate points to the matching row below. The most recorded is "An axle insecure or with loose fixing bolts", about 0.0 times per 100 failed tests.

Official wording

The defect clauses

5.1.1 (a)Dangerous
An axle fractured or deformed
5.1.1 (b)(i)Majorunder 0.1 per 100 fails
An axle insecure or with loose fixing bolts
5.1.1 (b)(ii)Dangerous
An axle insecure such that stability is impaired or functionality affected
5.1.1 (c)(i)Major
An axle with an unsafe modification
5.1.1 (c)(ii)Dangerous
An axle modified so that vehicle stability is impaired or axle functionality affected

Wording and categories reproduced from the DVSA inspection manual under the Open Government Licence. Frequencies are items per 100 failed class 4 tests across the DVSA anonymised MOT dataset; a clause with no figure was not recorded often enough to appear in any model’s top forty failure items. 0 of 5 clauses link to our own explanation.

Grading

What the categories mean

Dangerous: a direct and immediate risk to road safety or the environment. The vehicle fails and must not be driven until repaired, even to a garage.
Major: a defect that affects safety, the environment or other road users. The vehicle fails.
Minor: a defect with no significant effect on safety or the environment. Recorded on the certificate; the vehicle passes.

The full guide to defect grading

Section 5

Other sub-sections of axles, wheels, tyres and suspension

5.1.2Stub axles
5.1.3Wheel bearings
5.2.1Road wheel and hub
5.2.2Road wheel condition
5.2.3Tyres
5.3.1Springs
5.3.2Shock absorbers
5.3.3Suspension arms, rods, struts, sub-frames, anti-roll bars etc.
5.3.4Suspension joints, pins and bushes
5.3.5Gas, air and fluid suspension
5.3.6Complete suspension system

All sections of the manual

Common questions

What does 5.1.1 mean on an MOT certificate?: It refers to sub-section 5.1.1 of the MOT inspection manual, "Axles", within section 5, axles, wheels, tyres and suspension. The letter or letters after it — (a), (b)(i) and so on — identify the specific defect from the 5 listed here. 3 of them are graded Dangerous, 2 Major and 0 Minor.
Which axles defect is recorded most often?: "An axle insecure or with loose fixing bolts" (5.1.1 (b)(i)), recorded about 0.0 times per 100 failed MOT tests nationally.
Does a Minor defect fail the MOT?: No. a defect with no significant effect on safety or the environment. Recorded on the certificate; the vehicle passes. Major and Dangerous defects fail. A Dangerous defect also means the car must not be driven until it is repaired.