The short answer
A minor defect is a fault the tester found and wrote down, but one that does not fail the car. The GOV.UK result page puts it in one line: a car fails on dangerous or major problems, and may also come back with a list of minor or advisory problems to monitor or fix in the future. The difference from an advisory is that a minor defect is a defined item in the DVSA manual with a category attached; an advisory is the tester's note that something is on its way.
The most recorded minor item by a distance is a rear number plate lamp out when the car has two. On cars of fifteen years and over it appeared on about 1 in 18 first tests (5.5% of 31,405,150 tests in 2021 to 2025); on cars aged ten to fourteen on 4.4%. Both bulbs out would be a major defect and a fail. One out is minor, and most owners never notice it.
What the data shows
Each cell is the share of first tests in that age band that recorded the item as a minor defect. The rows are the single most recorded minor item in each defect family where one cleared our floor; the exhaust and seat belt families had none that did.
| Minor defect | Aged 3-5 | Aged 6-9 | Aged 10-14 | Aged 15+ |
|---|---|---|---|---|
| One rear number plate lamp out (of two or more) | 0.5% | 1.8% | 4.4% | 5.5% |
| Windscreen damaged, view not affected | 1.6% | 2.0% | 2.7% | 3.6% |
| Driveshaft joint (CV) boot badly deteriorated | 0.2% | 0.5% | 1.7% | 3.5% |
| Wiper blade defective | 1.2% | 1.0% | 1.1% | 1.4% |
| Suspension ball joint dust cover badly deteriorated | under 0.1% | 0.4% | 1.0% | 1.8% |
| Track rod end dust cover damaged, still keeping dirt out | 0.1% | 0.5% | 0.7% | 1.1% |
| Tyre obviously under-inflated | 0.1% | 0.1% | 0.3% | 0.4% |
| Flexible brake hose slightly twisted | under 0.1% | under 0.1% | 0.1% | 0.1% |
Three things stand out. First, the two big items are things you can see from outside the car: a bulb and a chip. Second, the rubber items, the driveshaft boot and the two dust covers, barely register on young cars and climb steeply with age, which is rubber perishing rather than anything going wrong. Third, one item not in the table because it only clears the floor on older cars: a headlamp lens slightly defective, recorded on 0.7% of tests aged ten to fourteen and 3.1% at fifteen and over. That is the hazing on old plastic headlamps, and it has a major cousin when the beam is affected.
Minor, major, advisory: the three words on a certificate
The DVSA manual gives every item a category. Take the number plate lamp: with two lamps fitted and one out, the manual's section 4.7 makes it a minor defect; with only one lamp fitted, or all of them out, it is major. Take the windscreen: damaged but not adversely affecting the view is minor; damaged and affecting the view is major. Take a wiper: a defective blade is minor; a blade missing or obviously not clearing the glass is major. The pattern is the same throughout. Minor is the version of a fault that does not yet affect how the car drives or how safe it is on the day.
An advisory sits outside this ladder. It is the tester's note about wear that is not yet a defect at all: a tyre close to the limit, a pad that is thinning, corrosion starting. Both minor defects and advisories appear on the GOV.UK MOT history for anyone to read, which is why a seller who says the car "passed clean" is worth a second look.
What to do with a minor defect
- Fix the bulb now. A number plate lamp costs pennies and takes minutes, and the second one will go eventually. Two out is a fail.
- Get the chip repaired while it is small. A minor windscreen result today is a major one once the crack runs, and the cold is coming.
- Ask about the rubber. A split driveshaft boot lets grit into the joint; a dust cover that has gone lets it into a ball joint. Both are cheap to replace before the joint behind them is worn, and expensive after.
- Change the wiper blade. It is the one item in the table that is as common on a three-year-old car as a fifteen-year-old one.
- Read the list on a car you are buying. A string of minor defects across several years is a car nobody looks at between tests. One or two is normal.
What this does not mean
A minor defect is not a hidden fail and does not make the certificate worth less; the car met the standard on the day. Nor does a clean certificate mean nothing is wearing. These shares describe what testers across the country recorded on very large groups of cars, and they say nothing about the condition of any one car. Several suspension dust-cover items share the same wording in the manual; the table quotes the most recorded of them.
Frequently asked questions
A fault the tester found that the DVSA manual classes as minor: it is recorded on the certificate and on the car's MOT history, but it does not fail the test. The car fails only on major or dangerous defects.
A minor defect is a defined item with a category in the manual, the lesser version of a fault that would be major if worse. An advisory is the tester's note that something is wearing and is not yet a defect. Both appear on the MOT history.
A rear number plate lamp out when the car has two: recorded on 4.4% of first tests on cars aged ten to fourteen and 5.5% on cars of fifteen and over, in 2021 to 2025. Windscreen damage that does not affect the view is next.
The test does not require it, but the item is on the record and most of them are the cheap early stage of a fail. A bulb, a wiper blade or a chip repair now saves a retest later.
Sources and method
Shares are tests recording the item as a minor defect divided by all class 4 first tests in the age band (test year minus first-used year), 2021-2025 pooled, across the model groups the item data covers: 33,793,352 tests aged 3-5; 50,103,915 aged 6-9; 44,980,002 aged 10-14; 31,405,150 aged 15 and over. Number plate lamp: 173,776; 883,448; 1,984,893; 1,719,221 tests. CV boot: 70,435; 267,612; 786,652; 1,114,750. Suspension ball joint dust cover (most recorded of several items with the same wording): 15,940; 209,273; 449,835; 575,809. Headlamp lens: 301,305 aged 10-14 and 965,844 aged 15 and over. Cells of 0.0% are written 'under 0.1%'. The exhaust and seat belt families had no minor item above the 20-test floor. A test can record several items, so columns do not add.
- DVSA anonymised MOT results, class 4 first tests, 2021-2025
- GOV.UK: MOT test result
- GOV.UK: MOT inspection manual, section 4, lamps, reflectors and electrical equipment
- GOV.UK: Check the MOT history of a vehicle
About these figures. Figures are computed by SortedCars from the DVSA anonymised MOT results dataset (class 4, first tests only, test years 2021-2025), published under the Open Government Licence v3.0. Pass rate = passes divided by first tests, with pass-after-rectification counted as a fail. No figure is shown for any group with fewer than 500 tests. Test class 4 only, first tests only; retests are excluded. Pass rates describe fleets, not individual machines: they reflect how cars were driven, maintained and used as well as how they were built, and beyond recorded mileage none of that is in the data. A well-kept example of a model with a weak average can still pass; a neglected example of a strong one can still fail. Alias spellings of a make are counted under one make name and all trims of a model under one model name, using SortedCars' grouping tables.
This article is general information drawn from published test records. It is not professional, mechanical or legal advice, and an MOT pass or a clean MOT history does not guarantee that a car is roadworthy today. If you are unsure about a car, have it inspected by a qualified mechanic. You can check any vehicle's MOT history free on the official GOV.UK MOT history service.
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