MOT performance
MOT failure “Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt”: how common it is and which cars get it
“Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt” (major defect, body, chassis and structure) was recorded as a failure on 1.36% of UK MOT tests in 2023–2024: 892,068 tests, the number 10 most common failure item. It is 13.5 times as common at 10 years old (1.51%) as at 3 (0.11%). It is most common at 17 years old (3.31% of tests).
892,068 tests with this failure, 2023–2024
Check a specific car's MOT history and running costsAt a glance
| Figure | Value | Basis |
|---|---|---|
| Share of MOT tests | 1.36% | 892,068 tests, 2023–2024 |
| Rank among failure items | #10 | by number of tests |
| Most common at | 17 years old | 3.31% of tests at that age |
| Models compared | 378 | models with enough tests |
How it changes with age
By fuel
Diesel: 1.86% of tests; Petrol: 1.07% of tests; Electric: 0.11% of tests; Hybrid: 0.11% of tests. Fuel groups differ in age and mileage, so these raw shares are not like-for-like; the model tables below are.
Models that fail on it most often
Relative to cars of the same age and fuel (1.00 = national rate for this item). Only models with enough tests for the difference to be clear are ranked.
| Model | Tests | Failed on it | vs similar cars |
|---|---|---|---|
| Citroen C3 Aircross | 54,618 | 2.07% | +1148% |
| Vauxhall Crossland | 118,672 | 1.84% | +1146% |
| DS DS 3 | 68,070 | 6.01% | +1032% |
| Peugeot 2008 | 246,579 | 6.40% | +931% |
| Dacia Sandero | 205,898 | 4.41% | +706% |
| Citroen DS3 | 146,860 | 10.76% | +607% |
| Peugeot Horizon | 17,208 | 7.04% | +583% |
| Mercedes-Benz Citan | 40,694 | 6.13% | +532% |
| Toyota Proace | 23,389 | 4.19% | +506% |
| Peugeot 208 | 402,103 | 4.16% | +501% |
Models that fail on it least often
| Model | Tests | Failed on it | vs similar cars |
|---|---|---|---|
| Toyota GR86 | 13,369 | 0.00% | -100% |
| London Taxis International TX4 | 26,655 | 0.00% | -100% |
| Hyundai i800 | 16,542 | 0.00% | -100% |
| Alfa Romeo Giulia | 12,881 | 0.00% | -100% |
| Jaguar XK | 16,340 | 0.01% | -100% |
| Mercedes-Benz SLK | 133,811 | 0.01% | -100% |
| Aston Martin Vantage | 15,831 | 0.01% | -100% |
| Land Rover Defender | 219,897 | 0.01% | -99% |
| Mercedes-Benz CLC | 17,704 | 0.02% | -99% |
| BMW 640 | 20,209 | 0.01% | -99% |
Makes that stand out on this failure
About this defect
The wording is DVSA's, from the MOT inspection manual. A high ratio for a model reflects its MOT record, which depends on maintenance and use as well as design. For one car, its own MOT history shows whether this has come up before.
Other common body, chassis and structure failures
- Exhaust system: has a major leak of exhaust gases · 0.78% of tests
- Exhaust system: system insecure · 0.29% of tests
- Integral vehicle structure condition: corroded to the extent that the rigidity of the assembly is significantly reduced · 0.15% of tests
- Chassis condition: or chassis has excessive corrosion, seriously affecting its strength within 30cm of a body mounting · 0.12% of tests
- Chassis condition: corroded to the extent that the rigidity of the assembly is significantly reduced · 0.08% of tests
- Door condition: cannot be opened from outside the vehicle · 0.07% of tests
- Fuel cap/sealing device: ineffective · 0.07% of tests
- System: component leaking · 0.05% of tests
Check the car you are looking at
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UK number plate or 17-character VIN
About this data. These are MOT test results, not a measure of mechanical reliability: a car's MOT outcome reflects its condition on the day, which depends on how it has been maintained and driven as well as how it was built. Figures cover class 4 vehicles (cars and light vans), normal tests only (retests excluded), outcomes pass, fail and pass after rectification at the station; vehicles at least 2.5 years old at test. Tests from 2023-01-01 to 2024-12-30. “Compared with similar cars” means compared with the national rate for cars of the same age, mileage band and fuel. Contains public sector information licensed under the Open Government Licence v3.0. Makes and models are matched to 73 Auto's vehicle catalogue; tests that can't be matched are left out rather than guessed. See how the MOT figures are produced.