Why do cars fail their MOT, and which checks prevent it?

Roughly one car MOT in four fails first time, and many of those failures come down to a light, a wiper blade or a worn tyre. We looked at every normal car MOT in Great Britain in 2025 to see what fails most often, how that changes with age, and which faults you can spot yourself before the test.

All figures are from DVSA’s anonymised MOT data for 2025 tests of cars aged three and over, with retests excluded. The data is provisional and was last updated on 15 September 2026.

What is the most common reason cars fail their MOT?

Lighting and electrical faults. 36.8% of failed car MOTs in 2025 had at least one, ahead of suspension at 32.4%, tyres at 23.5% and brakes at 21.8%.

Failures by DVSA category

There were 29,122,953 car MOTs in 2025 and 72.8% passed first time, so about 7.9 million failed. A pass after repairs at the test centre within the hour counts as a failure here.

Category (DVSA)	Share of failed tests	Approx. failed tests
Lamps, reflectors and electrical equipment	36.8%	2.92m
Suspension	32.4%	2.57m
Tyres	23.5%	1.86m
Brakes	21.8%	1.73m
Visibility	15.2%	1.20m
Noise, emissions and leaks	11.0%	0.87m
Body, chassis, structure	10.9%	0.86m
Steering	6.8%	0.54m
Seat belts and supplementary restraint systems	3.3%	0.26m
Road wheels	1.4%	0.11m
Identification of the vehicle	1.2%	0.10m

The approximate counts multiply each share by about 7.92 million failed tests. The pass rate is rounded, so treat them as estimates.

Why the shares add up to more than 100%

The shares are of failed tests, not of all cars. A car that fails on a broken light and a worn tyre counts once under lamps and once under tyres, so one failed test can appear in several rows.

That means it’s wrong to say 36.8% of cars fail on lights. The accurate version is that 36.8% of failed tests involved a lighting or electrical defect.

Related: MOT pass rates and common failures

Which specific faults fail the most cars?

Tyre tread below 1.6mm is the most widespread single failure, in the top ten failures for 384 of the 489 models with enough data. Wipers that don’t clear the screen come next, in 331 models.

The faults that turn up across almost every model

There is no national table of individual defects in our data, so we counted how many models have each item among their ten most common failures. That shows how widespread a fault is, not how many tests it failed.

Failure item (DVSA wording, shortened)	Models with it in their top ten	Out of
Tyres: tread depth below 1.6mm	384	489
Wipers: do not clear the windscreen effectively	331	489
Position lamp: not working	290	489
Brake pads: less than 1.5mm thick	270	489
Tyres: ply or cords exposed	235	489
Coil spring: fractured or broken	226	489
Tyres: cut deep enough to reach the ply or cords	226	489
Malfunction indicator lamp: on or not working	223	489
Washers: insufficient washer liquid	197	489
Stop lamp: not working	170	489

Models need at least 150 failed tests to get a defect list. Our page on how we count MOT defects and advisories explains the rest.

A brake light is the Fiesta’s commonest failure

“Stop lamp: not working” appeared on 18.0% of the Ford Fiesta’s 467,774 failed tests in 2025, about 84,000 failures. A brake light not working was its single most common reason to fail.

The Vauxhall Corsa shows the other side. Its commonest failure was a fractured or broken coil spring, on 17.5% of its 317,715 failed tests, a fault that is hard to spot at home.

Do the reasons for failure change as cars get older?

Yes. Three-year-old cars most often fail on tyres, ten-year-olds on suspension and 15-year-olds on lights: tyres were in 47.9% of failed tests for 2022 cars, suspension 31.6% for 2015 cars and lamps 46.0% for 2010 cars.

Top failure categories by year of first registration

First registered	Tests 2025	Pass rate	Tyres	Lamps	Suspension	Brakes	Visibility
2022	1,518,857	89.4%	47.9%	18.6%	5.4%	10.4%	21.7%
2015	2,327,555	72.6%	26.6%	30.7%	31.6%	20.3%	13.6%
2010	1,240,869	59.3%	18.4%	46.0%	41.2%	23.7%	14.2%

Category shares are of each year’s failed tests. The data can’t tell us why lighting faults rise so sharply with age.

Young cars fail on things you can see

Of failed tests on 2022 cars, 20.1% had a tyre cut deep enough to reach the ply or cords and 13.8% had wipers that didn’t clear the screen. Another 11.1% had tread below 1.6mm and 4.8% had too little washer fluid.

For 2015 cars, a broken coil spring led the list at 10.5% of failed tests. You can compare how a single year does on pages such as the 2015 Ford Fiesta MOT results.

How common are dangerous defects?

7.3% of all car MOTs in 2025 found at least one dangerous defect, about 2.1 million tests. A dangerous or major problem means an automatic fail.

What a dangerous result means for you

GOV.UK’s page on what happens after the MOT says you can only take the car away if your current MOT is still valid and no dangerous problems were listed. Driving a car that failed because of a dangerous problem can mean a fine of up to £2,500, a driving ban and 3 penalty points.

Minor problems and advisories don’t fail the test. They’re listed so you can monitor or fix them.

Dangerous defect rates vary by model

Among cars first registered in 2015, 10.3% of 2015 Renault Clio tests found a dangerous defect, against 4.6% for the 2015 Honda Jazz. Our most reliable cars ranking compares every model with cars of the same ages.

What can you check yourself before an MOT?

Lights, tyres, wipers, washer fluid, warning lights, the horn and seat belts can all be checked in a few minutes. Suspension, ball joints, brake pads and headlamp aim need a garage.

The quick checklist, mapped to real failures

Check before the test	What it prevents	Evidence from 2025 tests
Every light, including brake lights (use a helper or a wall), indicators and number plate lamp	Position lamp or stop lamp not working	Lamps in 36.8% of failed tests; stop lamp 18.0% of Fiesta fails
Tyre tread, cuts, bulges and pressures	Tread below 1.6mm, cuts to the ply or cords	Tyres in 23.5% of failed tests, 47.9% for 2022 cars
Wipers clear without smearing	Wipers not clearing the windscreen	In top ten failures for 331 models
Washer bottle topped up, jets working	Insufficient washer liquid	4.8% of failed tests on 2022 cars
Warning lights go out after start-up	Malfunction indicator lamp on	5.8% of failed tests on 2015 cars
Screen clear of stickers and clutter, no big chips in view	Visibility defects	Visibility in 15.2% of failed tests
Horn works, seat belts pull out, lock and retract, plates clean	Seat belt and identification defects	3.3% and 1.2% of failed tests

GOV.UK’s vehicle safety checks say car tyres need at least 1.6mm of tread across the middle three-quarters and around the entire tyre. The same page lists checking that all lights work, the brakes work and the windscreen, windows and mirrors are clean.

Brakes you can feel, pads you can’t see

You can notice if the car pulls to one side when braking, grinds or the parking brake doesn’t hold on a slope. Pads under 1.5mm, in the top ten failures for 270 models, usually need a garage to measure.

On 2015 cars, a malfunctioning tyre pressure monitoring system appeared on 6.2% of failed tests. If that warning light stays on, get it looked at before the test.

What you can’t check at home

Suspension is the second biggest reason for failure, at 32.4% of failed tests, and you can’t check it properly on a driveway. Broken coil springs and worn ball joints need the car lifted, and headlamp aim needs proper equipment.

The best defence is your last MOT’s advisories. “Tread depth: worn close to legal limit” was among the top advisories for 486 of 489 models and was noted on 18.6% of all tests of 2015 cars, so act on any advisory before the next test.

Related: MOT pass rates by area

What are the rules on MOT fines, exceptions and fees?

You can be fined up to £1,000 for driving without a valid MOT, unless you’re driving to a pre-arranged test or to somewhere to be repaired. The maximum fee for a car MOT is £54.85.

When you need an MOT and what happens without one

GOV.UK’s guide to getting an MOT says a car needs its first MOT by the third anniversary of its registration. After that it’s due every year on the anniversary of the last one.

You can get an MOT up to a month (minus a day) before it runs out and keep the same renewal date. That leaves time to fix a failure before the old certificate expires.

What an MOT costs

The official MOT fees set a maximum of £54.85 for a car with up to 8 passenger seats. Test centres can charge less but not more.

Before you book, a free vehicle check shows the car’s details, and it’s worth looking for any outstanding vehicle safety recalls at the same time.