The short answer
About 1 in 25 MOT tests on a car aged 10 to 14 fails with a side light or tail light out. That is 4.0% of 44,980,002 first tests between 2021 and 2025, and it is the most recorded light fault in the test. On a car at its first MOT the figure is 0.3%; on a car aged 15 or more it is 5.4%. Brake lights, headlamps and headlamp aim follow the same curve.
Taken as a whole, light faults go from 2.4% of tests on cars first used in 2021 to 11.0% on cars first used in 2006, about 1 in 9. The clocks go back at 2am on 25 October 2026, so from next week most evening journeys are in the dark. Ten minutes with the lights on in front of a wall catches nearly all of this, and bulbs other than headlamp aim are retested free if the car is back at the same centre by the end of the next working day.
Which light faults are recorded, by car age
Share of first tests recording each fault, 2021 to 2025. Age is the test year minus the year the car was first used.
| Item recorded | 3 to 5 yrs | 6 to 9 yrs | 10 to 14 yrs | 15 yrs and over |
|---|---|---|---|---|
| Position lamp | 0.3% | 1.2% | 4.0% | 5.4% |
| Stop lamp | 0.3% | 1.2% | 2.8% | 3.8% |
| Headlamp | 0.4% | 1.1% | 2.1% | 2.1% |
| Registration plate lamp(s) | 0.3% | 0.7% | 1.7% | 1.9% |
| Headlamp aim: projected beam image is obviously incorrect | 0.2% | 0.6% | 1.6% | 3.3% |
| Headlamp aim: too low | 0.7% | 1.0% | 1.5% | 1.8% |
Two things stand out. Side lights and brake lights are cheap bulbs and still lead on every car over six years old. On the youngest cars the top item is not a bulb at all but headlamp aim, at 0.7% of first MOTs, usually because a headlamp was changed or knocked and never set.
The new headlamp bulb rule
The DVSA rule change in special notice 05-26 took effect on 14 October 2026. Until then an LED bulb fitted into a headlamp made for a halogen bulb was an automatic fail, because the tester could not tell an approved bulb from a cheap one. Now the inspection manual lets the tester accept it if the bulb is ECE approved for that lamp and the manufacturer's approval sticker is fixed permanently to the car where the tester can see it. No sticker, a damaged sticker or one that does not match the bulb means the headlamp is rejected as a major defect.
The rule does not cover HID conversions, which remain a fail on cars first used on or after 1 April 1986, or complete LED headlamp units, which are judged on the ordinary lamp rules. If you have LED bulbs in halogen lamps and no sticker, refit halogen bulbs before the test.
Seven checks before the clocks go back
- Side lights and tail lights. Lights on, walk round. The single most recorded lamp fail on cars over six.
- Brake lights, including the high-level one. Reverse up to a window at dusk and press the pedal.
- Dipped and main beam. Both working, same colour, level with each other on a wall. The Highway Code says lights must be properly adjusted so they do not dazzle.
- Number plate lamp. Easy to forget: 1.7% of tests on cars aged 10 to 14.
- Indicators and side repeaters. All four corners.
- Rear fog lamp and its dashboard warning light.
- Clean the lenses. Road film dims a legal bulb.
Then open last year's test on the GOV.UK MOT history service. A lamp noted last year and fixed with a bulb is worth a second look; a corroded holder puts the same fault back.
What this does not mean
A 5.4% share on cars aged 15 and over means the large majority of those tests had no side light fault at all. These figures describe how millions of cars tested, not how yours will. A fifteen-year-old car with fresh bulbs and clean connectors is more likely to pass this part than a five-year-old nobody has looked at. The record says what the tester found, not why, and it pools every make together, so none of this is about any model.
Frequently asked questions
Yes. A mandatory lamp that does not work is a defect. A side or tail light fault was recorded on 4.0% of first tests on cars aged 10 to 14 between 2021 and 2025. Bulbs other than headlamp aim are retested free if the car is back at the same centre by the end of the next working day.
From 14 October 2026, only if the bulb is ECE approved for that lamp and the manufacturer's approval sticker is permanently fixed to the car where the tester can see it. Otherwise the headlamp is rejected as a major defect.
The record does not say why. It shows light faults on 11.0% of first tests on cars first used in 2006 against 2.4% on cars first used in 2021. Older bulbs, cloudy lenses and tired wiring are all possible; none is recorded.
At 2am on Sunday 25 October 2026, according to GOV.UK.
Sources and method
Item shares are failed class 4 first tests, 2021-2025, recording each lamp item, as a share of all first tests in the age band (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; age = test year minus first-used year). A test can record several items. Cohort shares are across models with 500 or more tests, by first-used year (2,021,332 tests first used 2021, 4,746,066 first used 2006).
- DVSA anonymised MOT results, class 4 first tests, 2021-2025 (data.gov.uk)
- GOV.UK: MOT special notice 05-26, approved LED replacement bulbs in halogen headlamps
- GOV.UK: MOT inspection manual, section 4, lamps, reflectors and electrical equipment
- GOV.UK: The Highway Code, annex 6, vehicle maintenance, safety and security
- GOV.UK: When do the clocks change
- GOV.UK: MOT retests after a repair
- 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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