Common MOT failures and advisories explained
What the items on an MOT result mean, how serious each one is and what fixing it usually involves, with the models that get each one most. Figures are per 100 initial MOT tests, from 33,842,940 tests in Great Britain in 2023 (DVSA MOT data for 2023, analysed by RegTail).
What MOT results mean
Since May 2018 every defect is graded. Dangerous and major defects fail; minor defects and advisories pass. GOV.UK
- Dangerous FailA direct and immediate risk to road safety or has a serious impact on the environment. Do not drive the vehicle until it's been repaired.
- Major FailIt may affect the vehicle's safety, put other road users at risk or have an impact on the environment. Repair it immediately.
- Minor PassNo significant effect on the safety of the vehicle or impact on the environment. Repair as soon as possible.
- Advisory PassIt could become more serious in the future. Monitor and repair it if necessary.
Brakes
| Defect | Fail | Advisory | Minor |
|---|---|---|---|
| Brake disc worn, pitted or scored | · | 8.8 | · |
| Brake disc significantly worn | · | 2.2 | · |
| Brake pads worn thin | 1.7 | 7.5 | · |
| Brake pipe corroded | 0.4 | 3.9 | · |
| Brake hose ferrule corroded | · | 0.3 | · |
| Brake hose damaged or perished | · | 0.2 | · |
| Binding brake | 0.3 | 0.9 | · |
| Brake effort fluctuating | 0.01 | 0.08 | · |
| Handbrake efficiency too low | 1.0 | · | · |
| Handbrake not working on one side | 0.1 | · | · |
Suspension and steering
| Defect | Fail | Advisory | Minor |
|---|---|---|---|
| Coil spring broken or corroded | 2.4 | 2.9 | · |
| Shock absorber leaking | 0.5 | 2.5 | · |
| Shock absorber bush worn | 0.08 | 0.1 | · |
| Suspension bush worn | 0.5 | 1.1 | · |
| Suspension ball joint worn | 0.7 | 0.3 | · |
| Anti-roll bar link worn | 0.2 | 0.5 | · |
| Anti-roll bar link dust cover split | 0.3 | · | 0.09 |
| Suspension joint dust cover split | 0.09 | · | 0.5 |
| Track rod end worn | 0.7 | 0.6 | · |
| Steering ball joint dust cover split | 0.08 | · | 0.4 |
| Sub-frame corroded | · | 0.6 | · |
| Suspension arm corroded | · | 0.5 | · |
| CV joint boot split | 1.1 | · | 1.1 |
| Wheel bearing play | · | 0.3 | · |
Tyres and wheels
| Defect | Fail | Advisory | Minor |
|---|---|---|---|
| Tyre tread depth low | 2.2 | 2.5 | · |
| Tyre damaged, cracked or perished | 0.7 | 4.4 | · |
| Tyre cords exposed | 1.0 | · | · |
| Wheel distorted or worn at the hub | · | 0.4 | · |
| Tyre pressure warning light on | 0.08 | · | · |
Corrosion and body
| Defect | Fail | Advisory | Minor |
|---|---|---|---|
| Excessive corrosion in the vehicle structure | 0.01 | 0.2 | · |
| Corrosion near a suspension mounting | 0.3 | 0.2 | · |
| Number plate illegible or deteriorated | · | 2.3 | · |
Engine, exhaust and leaks
| Defect | Fail | Advisory | Minor |
|---|---|---|---|
| Oil leak | · | 4.0 | · |
| Gearbox oil leak | · | 0.2 | · |
| Exhaust leak | 0.5 | 1.6 | · |
| Engine warning light on | 0.8 | · | · |
| Lambda reading out of limits | 0.2 | · | · |
| Airbag warning light on | 0.1 | · | · |
Lights
| Defect | Fail | Advisory | Minor |
|---|---|---|---|
| Side or tail light not working | 2.6 | · | · |
| Brake light not working | 1.9 | 0.1 | · |
| Headlight not working | 1.3 | · | · |
| Headlight lens slightly defective | · | · | 0.5 |
| Headlight aim out | 1.2 | · | · |
| Number plate light not working | 0.8 | · | 3.0 |
| Indicator discoloured or wrong colour | 0.07 | 0.6 | · |
| Side repeater not working | 0.08 | · | · |
| Rear fog light not working | 0.1 | · | · |
Windscreen, wipers and mirrors
| Defect | Fail | Advisory | Minor |
|---|---|---|---|
| Windscreen chipped or cracked | · | · | 2.5 |
| Wiper blade not clearing the screen | 2.1 | · | 0.7 |
| Screen washers not working | 1.2 | · | · |
| Mirror slightly damaged or loose | · | · | 0.1 |
At least this many in every 100 MOT tests, DVSA MOT data for 2023, analysed by RegTail.
Check a specific car
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Questions
What is the difference between an MOT advisory and a failure?
What are the most common MOT failures?
What are the most common MOT advisories?
How these figures are made. We counted the defects recorded at every initial MOT test (not retests) of cars and light vans in Great Britain in 2023 in the DVSA anonymised MOT dataset, 33,842,940 tests in all. Each item counts once per test. A failure is a major or dangerous defect, including one fixed during the test. A model's rate is the share of its tests where the item was recorded.
For each model we keep its 40 most frequent items, so a model where a defect is rarer than that is not listed, and figures for all cars are a floor. Defect names and explanations are ours, checked against the MOT inspection manual; DVSA's own wording is shown under each name.
Contains public sector information licensed under the Open Government Licence v3.0. RegTail's analysis of the DVSA anonymised MOT dataset, 2023 tests.