MOT performance
MOT failure “Exhaust system: system insecure”: how common it is and which cars get it
“Exhaust system: system insecure” (major defect, body, chassis and structure) was recorded as a failure on 0.29% of UK MOT tests in 2023–2024: 188,693 tests, the number 46 most common failure item. It is 16.1 times as common at 10 years old (0.34%) as at 3 (0.02%). It is most common at 18 years old (0.61% of tests).
188,693 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 | 0.29% | 188,693 tests, 2023–2024 |
| Rank among failure items | #46 | by number of tests |
| Most common at | 18 years old | 0.61% of tests at that age |
| Models compared | 338 | models with enough tests |
How it changes with age
By fuel
Petrol: 0.30% of tests; Diesel: 0.30% of tests; Hybrid: 0.02% of tests; Electric: 0.01% 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 |
|---|---|---|---|
| Vauxhall Crossland | 118,672 | 1.02% | +2342% |
| DS DS 3 | 68,070 | 1.47% | +1070% |
| Peugeot 2008 | 246,579 | 1.28% | +925% |
| Peugeot 208 | 402,103 | 1.89% | +883% |
| Citroen Dispatch | 95,578 | 2.50% | +876% |
| Citroen DS3 | 146,860 | 3.30% | +844% |
| Peugeot Expert | 111,048 | 1.89% | +668% |
| Citroen C3 | 404,896 | 1.96% | +515% |
| Fiat Scudo | 17,782 | 3.00% | +477% |
| Vauxhall Viva | 76,738 | 0.70% | +423% |
Models that fail on it least often
| Model | Tests | Failed on it | vs similar cars |
|---|---|---|---|
| Porsche Macan | 56,741 | 0.00% | -100% |
| MINI Paceman | 15,913 | 0.00% | -100% |
| BMW 640 | 20,209 | 0.00% | -100% |
| Aston Martin Vantage | 15,831 | 0.00% | -100% |
| SEAT Ateca | 87,288 | 0.00% | -98% |
| Porsche Cayman | 29,543 | 0.01% | -98% |
| Lotus Elise | 10,204 | 0.01% | -98% |
| Mercedes-Benz GLC | 150,770 | 0.00% | -98% |
| Mazda CX-5 | 128,119 | 0.00% | -98% |
| Skoda Karoq | 94,560 | 0.00% | -97% |
Makes that stand out on this failure
Makes whose cars record this failure clearly more or less often than comparable cars (same age, mileage and fuel):
- DS · 10.19× comparable cars
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
- Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt · 1.36% of tests
- Exhaust system: has a major leak of exhaust gases · 0.78% 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.