The 10 Most Common MOT Failures in the UK - And How to Avoid Them

Every year, millions of UK drivers face the MOT test with a mix of hope and dread. Some sail through. Others face unexpected bills that could have been avoided with a bit of preparation.

We've analysed 8,143,353 MOT tests across 1,091,402 vehicles to identify exactly what fails most often. The data comes from recent MOT records spanning popular models from Ford, Vauxhall, Volkswagen, and others. What we found confirms what mechanics have known for years: the same ten issues account for the vast majority of failures, and most are preventable.

This isn't about rare faults or model-specific gremlins. These are the everyday problems that catch ordinary drivers off guard, yet they're often cheap or free to fix if you know what to look for.

Why Do Tyres Cause Most MOT Failures?

Tyres dominate the failure statistics in a way that surprises many drivers. Across our dataset, tyre-related defects appear in roughly one in four MOT tests. The most common issue is tread worn close to the legal 1.6mm limit, often concentrated on the outer edge rather than across the full width.

This outer-edge wear pattern tells a story. It suggests underinflated tyres, misaligned tracking, or aggressive cornering. The Ford Transit shows this clearly: 22.3% of tests flag tyres worn on the outer edge, a consequence of heavy loads and commercial use patterns. But it's not just vans. The Vauxhall Insignia, typically driven longer distances by company car users, shows tyre wear in 37.2% of tests.

The second tyre problem is perishing and cracking, particularly on sidewalls. This appears in 14-20% of tests across most models. Perished tyres aren't necessarily old in calendar terms. They're often the result of cars doing low annual mileage, sitting idle for weeks while UV and weather damage the rubber. The Fiat 500, averaging just 4,536 miles per year, is a textbook example.

What Brake Problems Fail MOTs Most Often?

Brake defects are the second most common failure category, but they manifest differently depending on vehicle type and usage. Worn brake pads appear in 8-23% of MOT tests, with the Nissan Qashqai showing the highest rate at 23%. This makes sense: SUVs are heavier, brake components work harder, and many Qashqai owners rack up 7,795 miles annually on motorways where braking patterns differ from city driving.

The Transit vans reveal a more concerning pattern. Corroded brake pipes appear in 18.2% of tests, often described as 'across rear axle to both flex pipes'. This is critical-level corrosion, not surface rust, and it affects commercial vehicles that operate in all weathers, often carrying corrosive loads or encountering road salt without the benefit of regular washing.

Worn brake discs are the third brake issue, affecting 9-16% of tests. The description 'inner face corroded' appears repeatedly. This happens when brake pads don't make full contact with the disc surface, allowing moisture to corrode the untouched areas. It's particularly common on cars doing short journeys where brakes don't get hot enough to burn off surface moisture.

Modern brake systems are robust, but they need attention. Pads wearing thin can be spotted through wheel spokes on many cars. Listen for squealing, which often indicates worn pads. If your brake pedal feels spongy or the car pulls to one side when braking, get it checked before the MOT. According to RAC data, brake failures are among the easiest to prevent with basic maintenance.

Are Suspension Bushes a Common Failure Point?

Suspension arm bushes appear in the top three defects for several models, particularly the Ford Transit at 17-19% of tests. The description 'rear bush worn' or 'trailing arm bush starting to perish/separate' tells you this isn't catastrophic failure, it's gradual deterioration.

Bushes are rubber or polyurethane components that cushion metal suspension parts. They perish over time, especially on vehicles carrying heavy loads or operating on rough surfaces. Vans show higher rates because they work harder. The Transit Custom, hammering up and down motorways at over 10,000 miles annually, develops bush wear faster than a Polo pottering around town at 5,800 miles per year.

The challenge with bushes is that they're difficult for ordinary drivers to inspect. Wear often produces no obvious symptoms until it's advanced enough to affect handling. You might notice increased road noise, a less precise steering feel, or clunking over bumps, but by then the damage is done.

If you're buying a used van or high-mileage car, budget for suspension bush replacement. It's not catastrophically expensive, but it's labour-intensive, which means garage bills can surprise you. For cars approaching 60,000-80,000 miles, particularly those that have worked for a living, consider a pre-MOT inspection focusing on suspension components.

How Common Are Dangerous Defects Really?

The dangerous defect statistics deserve attention because they indicate immediate safety risks. The Vauxhall Vivaro shows a concerning 43.3% of vehicles have at least one dangerous defect flagged during their MOT life. The Vauxhall Insignia isn't far behind at 44.1%.

These aren't random failures. Both models are typically high-mileage vehicles. The Insignia averages 8,854 miles annually and often serves as a company car, accumulating motorway miles quickly. The Vivaro is a commercial van doing nearly 10,000 miles per year, often under load. Hard use accelerates wear, and when critical components like brake pipes corrode or suspension parts separate, the DVSA classifies them as dangerous.

Compare this to the 2018 Volkswagen Polo at just 16.2% dangerous defect rate. It's a newer car doing gentler miles (6,694 per year), owned by drivers who likely maintain it better. The dangerous defect rate often reflects the gap between how a car should be maintained and how it actually is maintained in the real world.

Check the gov.uk MOT history checker before buying any used vehicle. If previous tests show dangerous defects, ask questions. A pattern of neglect doesn't disappear just because the current test passed.

What Does the First MOT Tell You About a Car?

The first MOT happens at three years old, when the car is still relatively young. A strong first-time pass rate followed by declining pass rates in subsequent years signals accelerated deterioration. The 2016 Ford Fiesta shows this pattern: 85.8% pass their first MOT, but the overall pass rate across all ages drops to 79.5%.

That six-percentage-point gap suggests these cars don't age gracefully. By contrast, the 2017 Fiesta shows a narrower gap (91.1% first MOT, 84.8% overall), indicating better build quality or less aggressive early-life use. Model year matters, and sometimes one generation holds up significantly better than another.

The Vauxhall Vivaro shows the worst first-time pass rate in our dataset at 76.8%, with an overall rate of just 75.4%. These vans enter commercial service immediately and often skip the gentle running-in period that private cars enjoy. By their first MOT, they've already done hard miles, and it shows.

When buying a three-year-old car approaching its first MOT, don't assume it will pass. Get a pre-MOT inspection, particularly if it's a model with a weak first-time pass rate. The first failure can be expensive because it catches multiple deferred maintenance issues at once.

Does Higher Mileage Mean More Failures?

Annual mileage doesn't correlate neatly with failure rates, which surprises some people. The Ford Focus does 6,057 miles per year and achieves an 86.7% pass rate. The Ford Transit does 10,417 miles per year and manages 78.9%. You'd expect the Transit to fare worse given the extra miles, but the nine-point gap isn't huge considering the Transit is a commercial vehicle carrying loads and operating in harsher conditions.

What matters more is how those miles are accumulated. Motorway miles are easier on suspension and brakes than stop-start urban driving. A car doing 10,000 miles annually on motorways may arrive at its MOT in better shape than one doing 5,000 miles pottering around town, scraping speed bumps and kerbs.

Low mileage creates its own problems. The Fiat 500 averages just 4,536 miles per year. That sounds gentle, but it often means the car sits unused for weeks. Brake discs corrode, tyres perish, and rubber components degrade from lack of use. The 500's defect rate for perishing tyres (appearing in a significant portion of tests) supports this theory.

If you're buying a low-mileage car, don't assume it's been pampered. Check for signs of sitting idle: corroded brake discs, flat spots on tyres, perished rubber hoses. According to AA guidance, cars driven regularly tend to stay healthier than garage queens.

Which Models Show Specific Weakness Patterns?

Certain models develop predictable problems. The Nissan Qashqai, for instance, shows brake pad wear in 23% of tests, the highest rate in our dataset. Qashqai owners average 7,795 miles annually, often on motorways, and the extra weight of an SUV compared to a hatchback accelerates pad wear. If you own a Qashqai, budget for brake pads as routine maintenance, not a surprise expense.

The Vauxhall Corsa demonstrates a different pattern. Across multiple model years (2016, 2017, 2018), tyre-related issues dominate its defect list, but the car's reliability score varies significantly: 415/1000 for 2016, 385/1000 for 2017, then dropping to 368/1000 for 2018. This suggests inconsistent build quality or perhaps changes in the ownership demographic that affect how well these cars are maintained.

Ford Transits across all three years show remarkably consistent issues: tyres, suspension bushes, and brake components in roughly the same proportions. This consistency actually helps buyers and owners. You know what's coming. Budget for bushes around 60,000 miles, expect brake pipe corrosion if the van operates in winter conditions, and check tyres religiously.

The VW Polo stands out for consistency in a good way. Across 2016, 2017, and 2018 model years, it maintains pass rates between 84-85% and reliability scores of 447-537/1000. The defect patterns are predictable (tyres and brake discs), which makes pre-MOT preparation straightforward. This is a car that rewards basic maintenance with reliable MOT passes.

What Does 'Defects Per Test' Really Tell You?

The average defects per test metric reveals how fiddly a car is. The Ford Transit averages 2.1 defects per test (2016 model), while the Ford Fiesta from the same year averages 1.4. That 0.7 difference might not sound dramatic, but it means Transit tests are 50% more likely to identify multiple issues.

Commercial vehicles naturally score worse here because they work harder and defer maintenance longer. Owner-drivers of vans often run them until something breaks, unlike private car owners who might be more attentive to niggles.

The 2018 Ford Fiesta and 2018 VW Polo both average 1.1 defects per test, the lowest in our dataset. These are newer, lower-mileage cars still within their prime years. But the consistency across two different manufacturers suggests 1.1 is about as good as it gets for well-maintained three-to-five-year-old cars. If a similar-age car shows 1.8-2.0 defects per test, it's telling you something about either the model's durability or the typical owner's maintenance habits.

For buyers, this metric helps set realistic expectations. A high defects-per-test average doesn't mean the car is unreliable, it means MOTs will likely identify work needed. If you're handy with tools and can tackle minor jobs yourself, a slightly fiddly car might not bother you. If you pay garage labour rates for everything, those extra defects add up over years of ownership.

What Should You Check Before Your MOT?

The data hands you a clear priority list. Start with tyres. Walk around your car and check tread depth on all four corners, paying particular attention to the outer edges where wear concentrates. Use a tread depth gauge or the 20p coin test. Inspect sidewalls for cracks, bulges, or cuts. If you spot anything questionable, replace the tyre before the test.

Next, brakes. Look through the wheel spokes at the brake pads (if visible). Most modern cars have wear indicators that squeal when pads get thin, but don't wait for noise. Check your brake fluid level and inspect visible brake lines for corrosion. Test your brakes on a quiet road: they should feel firm and progressive, not spongy or grabby.

Under the car, if you can safely get underneath or use a torch to peer in, look for corroded brake pipes, particularly where they run along the rear axle. Surface rust is normal, but flaking or crusty corrosion means replacement is needed. This is especially critical on vans and older cars.

Lights are an easy check that many drivers skip. Turn on every bulb: headlights (dipped and main beam), sidelights, brake lights, indicators, fog lights, reverse lights, number plate light. Get someone to help or back up to a wall and watch the reflections. Bulbs are cheap, failures aren't.

Finally, windscreen condition. Small chips can often be repaired cheaply, but a crack in the driver's sight line will fail the MOT. Get chips sorted before they spread.

When Should You Pay for a Pre-MOT Check?

If your car has a history of failures, particularly for expensive items like suspension or brake pipes, a pre-MOT inspection by a garage makes financial sense. Many garages offer these for £20-40, and they'll identify issues you can then shop around to fix, rather than being stuck with whatever the MOT station quotes.

High-mileage cars benefit from professional pre-checks. Once you're past 70,000-80,000 miles, components that seemed fine last year can deteriorate quickly. Suspension bushes don't gradually get worse, they suddenly let go. A mechanic on a lift can spot this before the MOT tester fails you for it.

Vans and commercial vehicles should get pre-MOT inspections as standard practice. The Transit data shows that vans pick up multiple defects per test, and many of these (brake pipes, suspension components, chassis corrosion) aren't visible without proper access. The cost of an inspection is negligible compared to the cost of a failed MOT and rushed repairs.

For newer cars with clean MOT histories, you can probably skip the professional inspection. A 2018 Polo with one previous pass and no advisories doesn't need the same scrutiny as a 2016 Transit Custom with a catalogue of previous issues. Use PlateInsight to check the MOT history before deciding whether to pay for an inspection.

Frequently Asked Questions

The MOT isn't a lottery. The same issues fail cars year after year, and our analysis of over 8 million tests proves that most failures are predictable and preventable. Tyres, brakes, and suspension components account for the vast majority of defects, and all three can be inspected before test day.

Use PlateInsight to check any car's full MOT history before you buy. You get 5 free credits to see exactly what's failed on similar models, what advisories have been building up, and whether the car you're considering has been maintained properly. The data removes the guesswork from used car buying and helps you avoid the models and model years that consistently underperform in MOT tests.