Why cars fail their MOT

Every defect recorded at an MOT in 2025, ranked by how often it really happened. 42,728,066 tests, 92,473,454 recorded defects. The most common one in the country is a number plate bulb.

27.68%fail at first test

22.43%still fail after repair at the station

88.81%pass rate at 3 years old

59.95%pass rate at 13 years and over

What the categories mean

Every defect a tester records is put in one of three categories. Dangerous and major defects mean the vehicle has not passed. Minor defects are noted on the certificate, and they are worth putting right before they grow into something larger.

DangerousMajorMinor

The forty most common defects

Defect	Where	Category	Recorded in 2025
Inoperative in the case of multiple lamps or light sources	Registration plate lamp(s)	Minor	1,355,665
Damaged but not adversely affecting driver's view	Windscreen	Minor	1,210,655
Tread depth below requirements of 1.6mm	Tread depth	Dangerous	1,003,193
Not working	Position lamp	Major	976,383
Fractured or broken	Coil spring	Major	889,853
Does not clear the windscreen effectively	Wipers	Major	821,565
Constant velocity boot severely deteriorated	Joints	Minor	710,819
Less than 1.5 mm thick	Brake pads	Dangerous	709,059
Not working	Stop lamp	Major	682,330
Pin or bush excessively worn	Pins and bushes	Major	577,044
Has a cut in excess of the requirements deep enough to reach the ply or cords	Condition	Major	576,561
Lens slightly defective	Headlamp	Minor	568,374
Ball joint excessively worn	Ball joint	Major	552,501
Projected beam image is obviously incorrect	Headlamp aim	Major	547,762
Has ply or cords exposed	Condition	Dangerous	544,201
Constant velocity boot split or insecure, no longer prevents the ingress of dirt	Joints	Major	527,932
Ball joint dust cover severely deteriorated	Ball joint dust cover	Minor	517,249
Blade defective	Wipers	Minor	517,242
Not working on dipped beam	Headlamp	Major	503,317
Provides insufficient washer liquid	Washers	Major	501,423
Too low	Headlamp aim	Major	486,316
Ball joint dust cover damaged or deteriorated, but preventing the ingress of dirt	Track rod end	Minor	449,519
Inoperative in the case of a single lamp or all lamps	Registration plate lamp(s)	Major	421,026
Ball joint has excessive play	Track rod end	Major	410,574
Efficiency below requirements	Rbt (sp)	Major	405,626
Too high	Headlamp aim	Major	379,191
Has a serious fluid leak	Shock absorbers	Major	338,093
Inoperative or indicates a malfunction	Malfunction indicator lamp	Major	321,928
Ball joint dust cover no longer prevents the ingress of dirt	Linkage ball joint dust cover	Major	312,243
Excessively corroded	Rigid brake pipes	Major	303,554
Ball joint dust cover severely deteriorated	Linkage ball joint dust cover	Minor	284,327
Not working	Washers	Major	274,882
Prescribed area excessively corroded significantly reducing structural strength	Component mounting prescribed areas	Major	268,610
Ball joint excessively worn	Linkage ball joints	Major	260,289
Has a tear, caused by separation or partial failure of its structure	Condition	Dangerous	254,936
Significantly and obviously worn	Brake discs	Major	248,808
Has a major leak of exhaust gases	Exhaust system	Major	244,124
Excessively binding	Service brake performance	Major	226,071
Ball joint dust cover no longer prevents the ingress of dirt	Ball joint dust cover	Major	219,908
Inoperative or indicates a malfunction	Malfunction indicator lamp	Major	213,946

Where this comes from. DVSA publishes every anonymised MOT result and every recorded defect under the Open Government Licence. These are the whole of 2025 for cars and light vans. Our national failure rate comes out at 27.68%, against the 22.43% DVSA publishes after station repairs, which is how we know the sums are right.