What fails an MOT most often in the UK?

Lighting. Faults with lamps, reflectors and electrical equipment are 25.01% of all failure items, more than any other category, and one turns up in 10.89% of all tests. Suspension is second at 19.39% of defects, brakes third at 16.15%, tyres fourth at 12.86% and visibility fifth at 7.95%. Those five are 81.36% of all failure items, and 28.08% of cars and light vans failed first time.

The figures here are from the DVSA data set "MOT testing data for Great Britain", released 30 October 2025, financial year 2024 to 2025: the defect split from table DVSA/MOT/03, the test counts and failure rates from DVSA/MOT/01. Great Britain only: Northern Ireland MOTs are run by the DVA at government-owned centres and published separately. DVSA publishes classes 3 and 4 combined, and class 3 is three-wheelers under 450kg, so read "class 3 and 4" as ordinary cars and light vans. There is no published class-4-only rate. The latest quarter, April to June 2025, came in at 27.24%.

The full DVSA breakdown, ranked

Two percentages get quoted interchangeably and they are not the same. "% of tests" is prevalence: how many cars presented had a defect of that type. "% of defects" is share of the pile. The prevalence column cannot be summed into a failure rate, because one car can fail on several items at once.

Defect category	Share of all defects	Present in this % of tests
Lamps, reflectors and electrical equipment	25.01%	10.89%
Suspension	19.39%	8.73%
Brakes	16.15%	6.63%
Tyres	12.86%	6.39%
Visibility (screen, wipers, washers, mirrors)	7.95%	4.54%
Body, chassis, structure	6.34%	3.41%
Noise, emissions and leaks	5.80%	3.15%
Steering	3.50%	1.97%
Seat belts and SRS	1.62%	0.97%
Road wheels	0.74%	0.38%
Identification of the vehicle	0.62%	0.34%

Seat belt installation checks and speedometer defects are 0.01% each. A failed test averages 2.44 defects (2.05 major, 0.39 dangerous), so the typical fail is not one thing.

The most common failure is not the most dangerous one

This is the part most articles get wrong, and it changes what you tell a customer.

Tyres are only fourth by frequency. But they are 60.12% of all dangerous defects, and 4.74% of every test had a dangerous tyre defect on it. Brakes are second at 29.01% of dangerous defects and 2.58% of tests. Together, tyres and brakes are 89.13% of every dangerous defect DVSA recorded.

Lighting is common and cheap. Tyres are less common and are the thing that hurts people. Split the 28.08% by seriousness and you get 7.70% of tests failing with a dangerous defect and 20.38% failing on major defects only.

Dangerous, major and minor: what each means for the customer

DVSA's own definitions, worth quoting verbatim because they land better coming from the regulator than from the person holding the invoice.

• Minor: defects with "no significant effect on the safety of the vehicle or impact on the environment and minor non-compliances". The vehicle still passes.
• Major: defects that "may prejudice the safety of the vehicle, have an impact on the environment, put other road users at risk". The vehicle fails.
• Dangerous: "a direct and immediate risk to road safety or having an impact on the environment". The vehicle fails and should not be driven.

The rule tying them together, in DVSA's words: if a vehicle has any major or dangerous defects, it must be failed and a refusal notice issued.

Can the customer drive away after a fail?

Only if the existing certificate is still in date and nothing was listed as dangerous. Drive on a dangerous defect and GOV.UK's current guidance is a fine of up to £2,500, three penalty points and a driving ban. If the MOT has already expired, the only legal journeys are to a booked repair or a pre-arranged test, and the car still has to meet minimum roadworthiness standards on the way. Say that plainly at the counter, because most customers think the exemption is broader than it is.

Retest rules and the retest fee

• Left with you for repair, retested within 10 working days: partial retest, no fee.
• Taken away and returned by the end of the next working day: partial retest, no further fee, on a defined list including lamps (not headlamp aim), mirrors, seats, seat belts (not anchorages), horn, number plates, windscreen glass, wipers, washers, wheels and tyres, battery, wiring, doors, bonnet, bootlid, fuel filler cap, steering wheel, VIN, TPMS and rear reflectors.
• Taken away and returned within 10 working days: partial retest, and you can charge a partial retest fee. Anything else is a full retest at the full fee.

The partial retest fee is capped too. The DVSA MOT testing guide for test stations, section L, allows up to half the statutory maximum test fee, so £27.43 on a standard class 4 car. The full test cap is £54.85 for a class 4 car up to eight passenger seats, and £64 for nine to twelve seats with the seat belt check. Those windows are a quiet argument for your own test bay, covered in how to become an MOT testing station.

The two-minute pre-check, and its honest limit

Lighting (10.89% of tests), tyres (6.39%) and visibility (4.54%) are all checkable on a driveway with no tools, and together they are about 46% of all recorded defects. The Highway Code already requires most of it: lights, indicators, reflectors and plates kept clean and clear, screens free from obstructions, tyre pressures checked weekly when cold.

• Lights on, walk round: sidelights, dips, mains, indicators front and rear, brake lights, reverse, fogs, plate lights.
• Tread at least 1.6mm across the central three-quarters of the breadth of the tread, around the entire circumference. An illegal tyre carries a maximum fine of £2,500 and three penalty points per tyre, the level 4 maximum for a construction and use offence.
• Wipers that clear without smearing, washers that squirt, no screen damage in the swept area, plate legible, horn working, belts latching.

Be honest about the limit. Suspension and brakes are 35.54% of defects between them and neither is checkable on a driveway. A pre-check removes the silly failures. It does not make a car MOT-proof.

Around 1.8 million cars a year fail, then pass anyway

The initial failure rate is 28.08%. The final rate is 22.67%. The gap is roughly 1.8 million class 3 and 4 vehicles a year that failed initially then passed after rectification at the test station, out of about 33.1 million tests.

That gap is the whole commercial case for a pre-test check, in the regulator's own numbers. A bulb, a wiper blade or a screenwash top-up before the tester starts is the difference between "passed, here you go" and a conversation about why your garage failed their car. An MOT reminder that arrives with time to spare buys you the slot to do it, instead of a panic booking on the expiry date.

How to hand over advisories without sounding like a salesman

An advisory is recorded when an item is not deteriorated enough to warrant rejection: not defective yet, but wearing towards it. Advisories are not set in legislation and have no bearing on the result.

Say exactly that when you hand over the certificate. "This is not a fail and not a legal problem. The tester is noting the item is on its way out." Then give a rough timescale and a rough number and let the customer decide. An advisory with a photograph, a date and a measurement is a record. One delivered as "you'll want to sort that soon" is a pitch, and customers can tell. That is the point of a digital vehicle health check.

Is the MOT getting easier?

The class 3 and 4 initial failure rate has fallen from 40.00% in 2013-14 to 28.08% in 2024-25, but the categories changed on 20 May 2018 when the minor, major and dangerous system came in, so years either side are not strictly comparable. Since then it has fallen steadily rather than levelled off: 31.69% in 2019-20, 30.23%, 29.21%, 28.38%, a small rise to 28.58% in 2023-24, then 28.08%.

Two warnings about the source data

The DVSA/MOT/01 table published on 30 October 2025 has transposed class labels: the row marked classes 3 and 4 carries 41,423 tests, the row marked class 5 carries 33,128,617. The values are right and the labels are wrong, because 33 million minibuses is not a thing and 28.08% matches the clean MOT/03 table. Take headline rates from MOT/03. Separately, DVSA's annual report cites 42 million car, van and motorcycle tests for the same year against 35.2 million in the statistics: a different scope, and the larger figure almost certainly includes retests.

Second, there is no published breakdown of which lamp or which suspension component. DVSA publishes top-level categories only, so any article naming one specific blown bulb as the commonest MOT failure is extrapolating, not citing.

The bottom line

Lighting is the most common MOT failure. Tyres are the most dangerous, by a distance. 28.08% fail first time, the average fail carries 2.44 defects, and around 1.8 million a year are rectified on the spot before the customer ever sees a refusal notice. Check lights, tyres and the screen before the tester starts, and be precise about what an advisory is when you hand the certificate over. That is most of the avoidable gap, closed.

Autera records every check, advisory and photograph against the vehicle so the next MOT starts from what you found last time, and reminders go out early enough to leave room for the repair. Try free for 14 days → or see a demo.