MOT defect severity
Dangerous MOT defects: rates, the most common ones and the models most affected
7.8% of 65,477,892 UK MOT tests in 2023–2024 recorded at least one dangerous defect (5,141,819 tests, DVSA data), against 28.5% that failed for any reason. A dangerous defect means the car should not be driven until it is repaired. The rate rises from 4.3% at 3 years old to 10.9% at 15.
Data to 2024-12-30 · Page updated 2026-09-28 · Publisher: 73 Auto
- Dangerous defect
- 7.8%
- 5,141,819 of 65,477,892 tests
- Any minor defect
- 11.8%
- tests recording a minor defect
- Any advisory
- 51.0%
- tests with an advisory note
The most common dangerous defects
The most frequent is “Tread depth: tread depth below requirements of 1.6mm” (2.44% of all tests). Most of the top dangerous defects are in the tyres part of the test.
| Defect | Test area | Tests | Share of tests |
|---|---|---|---|
| Tread depth: tread depth below requirements of 1.6mm | Tyres | 1,598,898 | 2.442% |
| Brake pads: less than 1.5 mm thick | Brakes | 1,239,514 | 1.893% |
| Condition: has ply or cords exposed | Tyres | 888,583 | 1.357% |
| Condition: has a tear, caused by separation or partial failure of its structure | Tyres | 369,608 | 0.564% |
| Condition: has a bulge, caused by separation or partial failure of its structure | Tyres | 306,011 | 0.467% |
| Rbt (sp): efficiency less than 50% of the required value | Brakes | 185,735 | 0.284% |
| Brake discs: in such a condition that it is seriously weakened | Brakes | 165,044 | 0.252% |
| Condition: has a lump, caused by separation or partial failure of its structure | Tyres | 118,879 | 0.182% |
| Tread depth: tread pattern not visible over the whole tread area when minimum depth required is 1.0mm | Tyres | 82,050 | 0.125% |
| Stop lamp: all not working | Lights, reflectors and electrical | 69,957 | 0.107% |
| Ball joint: ball joint likely to become detached | Suspension | 55,124 | 0.084% |
| Rigid brake pipes: leaking on a hydraulic braking system | Brakes | 53,178 | 0.081% |
| Track rod end: ball joint worn to the extent there is a serious risk of detachment | Steering | 44,249 | 0.068% |
| Condition: has ply or cords damaged | Tyres | 39,729 | 0.061% |
| Pins and bushes: pin or bush likely to become detached | Suspension | 37,294 | 0.057% |
By age and fuel
Diesel 9.0%, Petrol 7.2%, Electric 6.0%, Hybrid 4.3% of tests — raw rates, before allowing for age.
| Age | Tests | Dangerous defect |
|---|---|---|
| 3 years | 3,907,416 | 4.25% |
| 5 years | 4,808,669 | 5.77% |
| 7 years | 5,283,534 | 6.84% |
| 10 years | 4,163,623 | 8.75% |
| 12 years | 3,355,332 | 9.98% |
| 15 years | 2,510,983 | 10.87% |
| 18 years | 1,392,716 | 10.80% |
| 20 years | 793,834 | 10.12% |
Models with more dangerous defects than similar cars
Of 320 models with at least 20,000 tests, 124 differ clearly (by at least 20%) from cars of the same age, mileage and fuel. 1.00 = the comparable rate.
| Model | Tests | Dangerous defect | vs similar cars |
|---|---|---|---|
| Chevrolet Matiz | 22,205 | 13.54% | 1.81× |
| Tesla Model 3 | 95,633 | 10.51% | 1.59× |
| Kia Carens | 30,774 | 13.11% | 1.56× |
| Peugeot 5008 | 66,454 | 10.73% | 1.49× |
| Mercedes-Benz Citan | 40,694 | 11.95% | 1.48× |
| Vauxhall Antara | 43,032 | 13.03% | 1.43× |
| Citroen DS4 | 20,814 | 13.09% | 1.40× |
| Mazda 5 | 22,878 | 15.05% | 1.40× |
| Smart Forfour | 48,547 | 8.01% | 1.37× |
| Fiat Tipo | 25,118 | 8.30% | 1.35× |
| Renault Kadjar | 136,997 | 7.98% | 1.34× |
| Renault Kangoo | 115,449 | 12.26% | 1.34× |
| Ford C-Max | 302,383 | 11.22% | 1.32× |
| Mitsubishi Mirage | 22,358 | 6.94% | 1.31× |
| MG MG3 | 39,968 | 6.43% | 1.31× |
Models with fewer dangerous defects than similar cars
| Model | Tests | Dangerous defect | vs similar cars |
|---|---|---|---|
| Fiat Auto Trail | 20,441 | 0.99% | 0.33× |
| Porsche 911 | 100,223 | 2.43% | 0.38× |
| Jaguar I-Pace | 30,624 | 2.30% | 0.39× |
| BMW M3 | 31,544 | 3.53% | 0.43× |
| Porsche Cayman | 29,543 | 2.65% | 0.43× |
| Bentley Continental | 29,070 | 2.61% | 0.44× |
| Porsche Macan | 56,741 | 2.61% | 0.45× |
| Audi A8 | 23,929 | 4.44% | 0.48× |
| Porsche Boxster | 65,604 | 3.72% | 0.51× |
| Subaru Impreza | 37,283 | 5.10% | 0.53× |
| Audi Q5 | 213,847 | 4.32% | 0.57× |
| Porsche Cayenne | 59,466 | 4.73% | 0.59× |
| Lexus UX | 20,230 | 1.94% | 0.61× |
| Lexus NX | 53,608 | 2.49% | 0.62× |
| Skoda Yeti | 152,100 | 4.86% | 0.62× |
By make
Among makes with an MOT page, SsangYong has the most dangerous defects for its cars' age, mileage and fuel (1.56×, 10.2% of 47,647 tests) and Aston Martin the fewest (0.31×, 1.5% of 43,571 tests).
Limitations
Official data: DVSA anonymised MOT results (2023–2024); defect categories (dangerous, major, minor) are DVSA's, from the May 2018 inspection manual. 73 Auto analysis: expected rates use national rates for each test's age, mileage band and fuel. Dangerous defects depend heavily on how a car has been maintained — worn tyres and brakes lead the list — so model differences are not a design-safety rating.
Has the car you’re buying had a dangerous MOT defect?
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Where these figures come from
- Anonymised MOT tests and results (2023 and 2024) — Driver and Vehicle Standards Agency (DVSA). Open Government Licence v3.0.
Figures labelled as 73 Auto estimates are our own analysis of these sources, set out in the methodology and data sources. To report a factual error, see corrections.