The Most Common MOT Failures (and How to Avoid Them)

The most common MOT failures are lighting and electrical faults, followed by suspension, tyres, brakes and visibility problems such as wipers, washers and windscreen damage. In DVSA's latest full-year figures, lighting and electrical defects were found on 10.44% of car and light van MOTs, more than any other area. Most of these failure reasons can be spotted, and often fixed, before the test.

What fails an MOT? Dangerous, major, minor and advisory

Every problem a tester finds goes into a category, and the category decides whether the car passes.

Driving a car that failed with a dangerous defect can mean a fine of up to £2,500, a driving ban and 3 penalty points.

The most common MOT failures: DVSA's latest data

DVSA publishes initial MOT failure reasons by defect category. These are the figures for cars and light vans (classes 3 and 4) from April 2025 to March 2026, covering about 33.3 million tests.

Source: DVSA MOT testing data for Great Britain.

Two things stand out. Failed cars rarely have just one problem: DVSA counts an average of 2.39 failure items per initial failure. And tyre faults are the most likely to be serious, with 4.47% of all tests recording a dangerous tyre defect, more than any other category.

1. Lighting and signalling faults

What fails: blown bulbs in headlights, brake lights and indicators; number plate lights that leave the plate unlit; cracked or missing lenses; lights showing the wrong colour; badly aimed headlights; and a broken main-beam warning light on the dashboard. On cars first used from 1 April 1980 the rear fog light is checked, and from 1 September 2009 the reversing lights too.

How to avoid it: Once a month, and again a few days before the test, check every light with a helper or against a reflective garage door. After changing a headlight bulb, make sure the beam isn't pointing too high or low. Lamps (except headlight aim) qualify for a free partial retest if you return to the same test centre by the end of the next working day, but a quick check beforehand saves the trip.

2. Suspension

What fails: broken or corroded springs, leaking or ineffective shock absorbers, worn joints and bushes, and damaged or badly corroded suspension arms and mountings. Suspension made up a fifth of all failure defects in DVSA's latest figures.

How to avoid it: You can't inspect most suspension parts at home, but you can notice the symptoms. Listen for knocks, clunks or creaks over bumps, and watch for the car sitting lower at one corner, leaning in corners or wearing its tyres unevenly. Get these looked at during a service, and treat any suspension advisory on last year's MOT as a job to book, not a note to ignore.

3. Tyres

What fails: tread below the 1.6mm legal minimum (a dangerous defect), cuts deep enough to reach the cords, lumps and bulges, tyres of different sizes or construction on the same axle, damaged valves, and a faulty tyre pressure monitoring system on cars first used from 1 January 2012. An obviously under-inflated tyre is recorded as a minor defect.

How to avoid it: Do the 20p test every month: if you can see the coin's outer band in the main grooves, measure the tread properly. Check the sidewalls for damage, keep pressures at the handbook figures, and replace tyres before they reach the limit. Our guide to legal tyre tread depth in the UK explains why many safety experts suggest replacing at 3mm.

4. Brakes

What fails: worn pads and discs, uneven braking from side to side, poor overall braking efficiency, binding brakes, a parking brake that doesn't hold, corroded or leaking brake pipes, and ABS or electronic parking brake warning lights showing a fault. Brake fluid significantly below the minimum mark is a major defect, and if no fluid is visible it's dangerous.

How to avoid it: Don't ignore grinding, squealing, a spongy pedal or the car pulling to one side. Check the brake fluid level through the reservoir, and keep up with servicing so pads, discs and fluid are replaced on schedule.

5. Visibility

What fails: windscreen damage larger than 10mm in zone A (a 290mm-wide area centred on the steering wheel) or larger than 40mm elsewhere in the wipers' swept area, wipers that don't clear the screen, washers that don't work or have no fluid, objects blocking the driver's view, and missing or damaged mirrors.

How to avoid it: Top up the screenwash, replace smearing wiper blades, and have chips repaired while they're small. Take sat nav mounts and dangling air fresheners out of the swept area before the test.

Other common reasons for MOT failure

• Body, chassis and structure: excessive corrosion or damage in key areas, and sharp edges that could injure someone. Corrosion within 30cm of a seatbelt anchorage is treated seriously.
• Noise, emissions and leaks: a noisy or leaking exhaust, emissions over the limit, an engine management light showing a fault, heavy smoke, a tampered diesel particulate filter, and fluid leaks that make a pool more than 75mm across within five minutes.
• Steering: too much free play at the wheel, worn joints, power steering problems and an electronic power steering warning light.
• Seatbelts and airbags: cut or frayed webbing, faulty buckles or retractors, and an airbag warning light showing a fault.
• Number plates and VIN: wrong fonts or spacing, damage, dirt or tinted covers that make the plate hard to read, and a missing or illegible vehicle identification number.

What happens if your car fails its MOT?

You'll get a refusal of an MOT test certificate listing the defects, and the result is recorded on the MOT database. You can only drive the car away if your current MOT is still valid and no dangerous defects were found.

What the retest costs depends on what you do next. A car left at the test centre for repair and retested within 10 working days gets a free partial retest, and some items, such as lamps, tyres, wipers and mirrors, can be retested free if you return to the same centre by the end of the next working day. Otherwise expect a partial retest fee within 10 working days, or the full fee after that. Our guide to how much an MOT costs sets out every scenario.

If you think a fail is wrong, discuss it with the test centre before any repairs are made. You can then appeal to DVSA within 14 working days of the test.

How to spot a likely fail in your MOT history

Your car's MOT history is the best early warning you have. Every test since 2005 is recorded, along with the mileage, any defects and the tester's advisories. Look for:

1. Advisories from the last test. Typical examples mention tyres wearing close to the limit, worn brake pads or discs, corrosion, or worn suspension parts. These are often next year's fails.
2. Repeat advisories. If the same item has been flagged two years running, it's probably close to the point where it fails.
3. Past failures and how they were fixed. If a fail was cleared at a retest, the record shows when.

You can see all of this in our free MOT history check. It's also invaluable when you're buying, which is why it features in our used car buying checklist, and our guide on how to check MOT history explains what each part of the record means.

Next steps: give your car the best chance of passing

1. Look up your car in the MOT history check and list any advisories.
2. Get those items quoted and fixed before the test, ideally at a service. Our car service page helps you book one.
3. Work through our 20-point MOT checklist a week before the test.
4. Compare local garages and book your MOT early, up to a month (minus a day) before it's due, so you keep your renewal date.