The Most Common MOT Failures in the UK (and Why)

How many cars fail their MOT first time?

In the 2024 to 2025 financial year, 26.22% of cars failed their MOT first time, according to the DVSA's MOT testing data for Great Britain. That's roughly one in four — not the "one in three" figure you'll see repeated on a lot of car blogs. This guide runs through what actually fails cars, ranked by how often, then how to catch each one before you book the test.

One thing to be clear on up front: this is about actual failures, not advisories. An advisory is a tester's note that something is wearing but isn't bad enough to fail the car — a different thing entirely, which we cover in MOT advisories explained. Here we're only talking about the faults that stop a car passing.

For the 2024 to 2025 financial year, the DVSA recorded an initial failure rate of 26.22% for the class that covers cars. In plain terms, around a quarter of cars fail at the first attempt.

A note on how the DVSA counts this: it reports classes 3 and 4 together — "cars, vans and passenger vehicles with up to 12 seats" — so the figure covers ordinary cars alongside light vans and small passenger vehicles, not cars in complete isolation. It's the closest official measure of the "will my car pass?" question, and it comes directly from the DVSA's published statistics rather than a garage's estimate.

"Initial" failure matters too. Some of those cars pass on the same visit once a minor fault is fixed at the test station, so the number that ultimately stay failed is lower. But the initial rate is the honest one for a buyer or owner: it's the share of cars that turn up and don't pass as they are.

The most common MOT failure categories, ranked

Below are the defect categories cars fail on most often, from the DVSA's "class 3 and 4 vehicles: initial failures by defect category" data for the 2024 to 2025 financial year.

One important thing about these percentages. Each figure is the share of all tests that failed on that category — so 10.89% means roughly one in nine cars tested failed on lighting somewhere. They don't add up to 100%, and they're not meant to: most cars pass, and a single failed car can fail on several categories at once. Read them as "how likely is a car to trip up here", not as slices of a single pie.

Lighting and signalling

Lighting tops the table every year, and it's the most avoidable of the lot. A blown bulb, a dead indicator, a misaligned headlight, a cracked lens or a number-plate lamp that's stopped working will all fail a car — and most drivers never notice, because you rarely see your own lights working from the driver's seat.

Suspension

Suspension is second, and harder for an owner to self-diagnose than lighting. Failures come from worn shock absorbers, tired bushes, corroded or broken springs, and play in the joints — all things that develop slowly as a car ages.

Pre-check: listen for knocks or clonks over speed bumps and potholes. Look underneath for obvious corrosion or fluid leaking from a shock absorber. Uneven tyre wear across the tread is often the first outward sign that something in the suspension or steering isn't right.

Brakes

Brakes are a high-wear safety item, so it's no surprise they're near the top. Worn pads or discs, an ineffective handbrake, or a braking imbalance between the wheels will all fail a car.

Pre-check: listen for grinding or squealing, and feel for the car pulling to one side or a spongy, long-travel pedal. If the handbrake needs a lot of clicks to hold on a hill, that's worth sorting before the test.

Tyres

Tyres come fourth, and unlike suspension the rule here is a hard legal line. The MOT inspection manual requires the tread to be at least 1.6mm deep within the central three-quarters of the breadth of the tread and around the entire outer circumference of the tyre. Below that, or with a cut, bulge or the wrong type of tyre fitted, the car fails.

Visibility

Visibility failures are about the driver's view of the road: a chip or crack in the windscreen within the area swept by the wiper on the driver's side, worn wiper blades that smear, or washers and jets that don't work. All cheap to fix and commonly neglected.

Structure, emissions and the rest

Further down the DVSA's ranking, but still worth knowing: body, chassis and structure failures (usually corrosion near a structural or load-bearing brake or suspension mounting point), noise and emissions failures, and steering faults. Number-plate condition, seat belts and mirrors sit lower still but do catch cars out. These are grouped here because they're less common than the top five, not because they're minor — a structural corrosion fail can be an expensive one.

Why these faults happen — the pattern behind the numbers

Look at the top of that list and a pattern jumps out: lighting, suspension, brakes, tyres and wiper visibility are all consumable, wear-and-tear items. They're not one-off mechanical disasters — they're the parts that quietly wear out on every car and need routine attention.

That's good news, because it means most MOT failures are avoidable with basic upkeep rather than down to bad luck. A bulb, a set of wiper blades, some screenwash and a tyre-tread check between them cover a big share of the reasons cars fail. The cars that sail through are usually the ones whose owners keep on top of exactly these small jobs.

How to avoid an MOT failure: a pre-test checklist

Twenty minutes the weekend before your test covers most of the common failures:

• Lights: walk round with everything switched on — sidelights, dipped and main beam, indicators, hazards, brake lights, fog lights and the number-plate lamp. Replace any dead bulbs.
• Tyres: do the 20p test around each tyre and check for cuts, bulges and uneven wear. Don't forget tyre pressures.
• Visibility: top up the screenwash, check the washers spray and the wipers don't smear, and look for chips or cracks in the driver's view.
• Brakes: listen for grinding and feel for pulling or a soft pedal on your next drive; check the handbrake holds on a slope.
• Suspension: listen for knocks over bumps and glance underneath for leaks or heavy corrosion.
• Number plate and screen: make sure plates are clean, secure and legible, and the windscreen is clear.

None of this guarantees a pass — a hidden brake or suspension fault can still catch you out — but it clears the faults that make up most of the DVSA's failure list.

Buying a used car? What a failure pattern can tell you

If you're weighing up a used car rather than sitting your own MOT, the same categories are worth reading in a different way. A car's MOT history shows not just whether it passed, but what it failed on and when — and the pattern matters more than any single line.

A one-off brake failure that was fixed and retested is normal ownership. The same category failing repeatedly — brakes failed at two of the last three tests, say, or corrosion cropping up more than once — points to a car that's either been run hard or maintained on the cheap. That's a reason to look harder and a fair point to negotiate on, not necessarily a reason to walk.

This is a different signal from advisories, which flag things that were wearing but didn't fail — our MOT advisories explained guide covers how to read those. For actual failures, you want the full test record. Our free MOT check tool pulls a car's complete MOT history from just the number plate, including every pass and fail and the reasons for any failure, so you can spot a repeat-failure pattern before you hand over any money.

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