12 Most Common MOT Fails and How to Avoid Them

Any and every car older than three years needs to pass an annual MOT test to certify it is roadworthy. You can't drive on UK roads without it. Failing an MOT is relatively common, but could be a tremendous inconvenience. Luckily, there are several easy fixes that can protect you from failing yours. That all starts with knowing where to look.

Every year, millions of vehicles fail their MOT test, meaning they don't meet the minimum safety and roadworthiness requirements set forth by the government.

Not everything warrants a failure. For small defects and minor issues, the examiner might issue an MOT advisory or allow you to fix them after your test instead.

However, there are plenty of seemingly minuscule issues that can cause you to fail.

To ensure you aren't one of the hundreds of thousands who fail every year, it's always a good idea to survey your vehicle yourself beforehand. That way, you can fix problems on your own terms rather than the garage's.

In this article, we'll show you the 12 most common areas of contention during MOT tests. That way, you'll know where to look.

Why do cars fail their MOT test?

To put it bluntly, there are a lot of reasons cars fail their MOT test. Since the inspector examines everything from your buttons and headlights to your suspension and exhaust, there can be quite a few issues in between.

According to 2023 data from the DVSA, 10,010,559 cars failed their initial MOT check. That's about one in three cars.
Other data shows that nearly 20% of all vehicles fail due to blown bulbs, broken signals and other lighting issues.

Besides lighting, the top causes of MOT test failure are:

• tyres
• brakes
• suspension
• exhausts and emissions
• visibility (i.e., anything affecting the driver's view of the road)

Weight also plays a role in pass/fail rates. The DVSA also states that heavier cars (which include electric vehicles) are statistically more likely to fail their MOT test.

That said, you can fail your MOT for anything on the inspector's checklist. That's why it's important to be aware of your vehicle's condition ahead of time.

Common MOT Fails: Essential Checklist

To help you understand your vehicle's condition and where to look for potential problems, these are the 15 reasons for MOT failure we see the most.

Registration plates

Registration plate flaws are some of the easiest to spot. They're also a major issue because your plates are your car's main identifiers. If they aren't visible, your car could be indistinguishable from another one.

Most of the time, registration plates cause vehicles to fail due to deterioration. Whether your plates are faded, excessively scratched or simply too dirty to read, your inspector will fail you for it. You can also fail if your plates are cracked or damaged.

Most of the time, registration plates are an easy fix. Usually, all you have to do is polish them off and you're good to go. If you have to replace them, it's a good idea to do so before your MOT test.

Body and structure

Your vehicle can immediately fail its MOT if the structural integrity is severely compromised. A little misalignment won't fail you, but you'll have to make sure that all of the edges and seams on your vehicle are tightly secured.

To determine whether your vehicle is roadworthy, your inspector will look at the following areas:

• Load-bearing parts such as the doors, chassis and boot
• Engine mountings and underbody to check for sagging, rust or corrosion
• Bonnet shut lines and fastening
• Bumpers
• Spare wheel carrier (if you have one)
• Towing bracket (if you have one)

Basically, if any of these parts are severely damaged or corroded, your car will fail. If, upon looking closer at these elements, you notice they could affect your car's performance, it's best to take them to a mechanic before your inspection.

Seat belts and airbags

Seat belts and airbags are life-or-death features. If they're faulty or broken at all, you'll get a failing score.
Your inspector will automatically fail you for any of the following problems:

• A seat belt missing or inoperative
• A seat belt that isn't securely fixed
• Missing seat belt buckles
• Any kind of significant damage to the seat belt webbing, such as excessive fraying, burns or tears
• Inoperative airbags
• Faulty airbag sensors or mechanisms

As part of the inspection, your tester will also look into how effectively your seat belts and airbags would protect you if the car were to be involved in an accident. They'll do this by tugging the seat belts and running a diagnostic test the airbag sensors.

Steering

Your tester will check the integrity of your vehicle's steering system both externally and by using the steering wheel.
If you fail because of your steering system, it's probably for one of these reasons:

• Slackness — If the steering wheel moves too far in either direction without the wheels turning, you've got a slack issue that needs to be addressed before your vehicle is roadworthy.
• Detachability — Loose, wobbly or otherwise unstable steering wheels will indicate an immediate (fail-worthy) issue.
• Power assist — The tester will check this by simply turning the steering wheel with their hand. They want to know how easily it turns and if there are any odd noises coming from it.
• Power steering fluid — Another quick check involves looking at the level and colour of the fluid. Below the minimum level results in a fail.
• Wear and tear — A worn-down steering wheel or column might cause a fail in some cases, but less often.

Steering problems aren't always as easy to fix right away. If you've noticed a problem with your steering, it's best to take it to a mechanic and get it looked at properly before scheduling your MOT.

Fuel and exhaust

If you're taking an MOT test for an electric vehicle, you won't have to worry about advisories or failures due to fuel or exhaust. But for petrol and diesel cars, these are some of the most common areas for failure.

Your inspector will check the following:

• Fuel caps — The cap should be secure and in its proper place. Depending on your car's age, they'll also look at emission control devices (like a catalytic converter).
• Exhaust system — This includes checking for any holes, leaks or corrosion.
• Exhaust noise — The engine should be silent when idle and not too loud when revved. If you have a modified car with aftermarket exhaust, this could be an easy way to fail.
• Fuel tank leaks — If the inspector suspects that your fuel tank is corroded or leaking, they'll look further into it with additional tests.

The most important thing to check for ahead of your MOT test is your emissions. The readings for this will depend on the age of your car. If they're too high, you'll fail right away.

Tyres and wheels

UK law states that tyres require 1.6mm of tread depth to pass the MOT test. That's the equivalent of a 20p coin in the grooves of your tyre.

If your tyre treat is nearing that depth, you won't fail right away. But your inspector will issue you an advisory. And in the event an officer notices low tread depth while on the road, you could be on the hook for up to £2,500 in fines.

In addition to tread depth, your tester will check for bulges, cuts and cracks on the exterior. They'll also look at whether or not the sizes match and if they are correctly fitted to your car. These issues put your tyres at a high risk of a blowout, so they'll usually cause a fail.

Brakes

If you haven't replaced your brake pads or discs after 50,000+ miles, you're almost guaranteed to fail in this category. In fact, that's part of the reason brakes are one of the most common reasons for MOT failure.

Your tester will look at your brakes from all angles, examining the following areas primarily:

• Brake fluid
• Brake pads
• Parking brake
• Brake discs
• Hoses and lines
• ABS system

A telltale sign your brakes need restoration is a squealing or grinding noise when you press down on the pedal. If you have this issue, you've probably noticed it while driving already.

Sometimes, brakes are more worn down on one side than the other. If your brakes are uneven, you'll notice your car pull slightly to one side as you come to a stop.

Less obvious is the smoothness of the brake discs. Look closely at them and see if there are any grooves (which start to form after thousands of miles). Grooves are terrible for the rotor and can cause your steering wheel to vibrate when you slow down.

Electric vehicle owners need to pay extra close attention to their brakes. Since EV batteries recharge through regenerative braking, brakes tend to wear down faster on electric car wheels.

Suspension

Suspension issues are also up there with the most common MOT failures.

The inspector will pay close attention to the following areas:

• Shock absorbers — Your tester will check for any leaks, corrosion or abnormal movement.
• Springs — This includes leaf and coil springs (both front and rear). They'll look at each individually to make sure that they aren't sagging, broken or otherwise damaged.
• Ball joints — Any disconnected or worn-down ball joints will result in an automatic failure.

If you've ever hit a pothole and felt like your car was going to fall apart, then you probably need to restore your suspension. Even if your MOT test isn't coming up for a few months, you definitely want to take care of these issues sooner rather than later. Serious suspension repairs can cost thousands of pounds.

It's worth noting that you might be forgiven for a leaky shock absorber or broken spring if you can prove that it was caused by a pothole or some other type of accident. But even if you are, the tester would still give you an advisory for these issues and recommend you fix them quickly.

Lights and signaling

Lights account for around one in five MOT failures, earning them the spot on the list of most common fails. On the bright side, they're also quite cheap to fix in many cases.

There are a lot of different lights your tester will look at during your MOT test:

• Brake lights
• Headlights
• Indicators
• Reverse lights
• Hazard lights
• Number plate lamps
• Fog and spotlights (if applicable)
• Buttons and switches that activate all these features
• Overall light condition (e.g., cracks, dirt, and water inside the lamp)

The inspector will check each of these individually to make sure that they're in good condition. That includes whether the bulbs are broken, if they turn on when you press the switch and if their colour is correct (i.e., not too bright or too dim).

Your car's plastic light lenses will probably get misty over time. To be proactive, we recommend purchasing a kit to clean them off in addition to checking for flaws.

Windscreen

Visibility issues are among the most frequently cited reasons for failed MOT tests. That starts with your windscreen.
Your tester will look at your windscreen for the following:

• Cracks, chips or scratches
• Any discoloured or fogged up areas that cause visibility issues
• Damage caused by stone chips or other marks
• Debris inside the windscreen wipers
• Wiper blades themselves

Depending on the condition of your windscreen, you might get away with a minor chip. But if it's larger than 40mm, you'll fail immediately.

Excessive exhaust emissions

According to the abovementioned report from the DVSA, 11.03% of all MOT failures (1,104,297 in total) result from emissions problems. You probably don't have the means to check your emissions levels yourself. But you can take a few steps to reduce the chance of failure in this area:

Make sure your engine is running well with no oil leaks

• Take your car for regular services and tune-ups
• Replace air filters and spark plugs on-time
• Check your exhaust for blockages or holes

Newer vehicles won't have as many problems with emissions. To keep it that way, make sure you keep up with the manufacturer's recommended maintenance schedule.

Mirrors

Missing rear-view mirrors, although uncommon, are a major fail. More often, someone would fail their MOT due to their mirrors obstructing visibility and posing a safety hazard.

Loose mirrors, small cracks and dirtiness are all minor faults that can result in an advisory. But if the tester finds a major fault, your car will fail immediately.

To avoid this from happening, make sure you check your mirrors before every drive and wipe them off regularly if they get smudged or dusty.

What cars are most likely to fail the MOT?

Data from MOT stats reveals that Chevrolets are the least likely to pass their MOT test out of the most popular car brands. With a pass rate of just 54.68%, only about one in every two Chevrolets passes the first time in the UK.

Renault, Dodge and Saab come in close after Chevrolet with a pass rate ranging between 61.88% and 62.32%.

This data should be taken with a grain of salt, though. It accounts for all cars, not just newer models. While nearly 61,000 UK motorists took their Saabs in for an MOT test, the company discontinued production in 2011.

An old Saab is likely to fail its MOT due to its age and lack of maintenance. We suspect the same circumstances affect other brands like Chevrolet and Renault, which produce widely popular (and reliable) cars but have a comparatively low pass rate.

How to avoid MOT failure

Really, there are three things you can do to prevent your car from failing its MOT test:

• Maintain it well so issues don't show up as quickly or frequently.
• Look for problems and fix them proactively.
• Examine your car beforehand. If there are any issues, fix them ahead of your appointment.

Failing your MOT test isn't the end of the world, though. Most of the time, you'll have to make small fixes the garage can handle within the same day. If your car had something significantly wrong with it, you probably couldn't drive it to the test centre.

For a complete rundown on how to prepare for and pass your MOT test, check out our complete MOT checklist.

Wrapping up

If you fail your MOT, chances are good it isn't the end of the world. Millions of people fail theirs every year.
But it is a tremendous inconvenience. After all, who wants to spend more time and money at the garage?

Maintenance and proactive problem-solving are the keys to passing any MOT test. If you're concerned about a particular component or area of your car, give it a hard look before the test and fix any issues you find.

If you want to fix your vehicle on your own terms (i.e., at a different garage from your test centre), we recommend booking your MOT appointment a few weeks before your MOT expires. That way, you'll have your old certificate to permit you to drive.

Want to learn more? These are the questions our customers ask us the most.

What happens if a car fails MOT?

If your car fails its MOT, it is no longer roadworthy. It cannot leave the garage until its safety and emissions issues have been fixed. Usually, this takes a few days or less, with some fixes taking place on the same day as your test. The only exception to this rule is if last year's MOT certificate is still valid. In that case, you still have legal proof your car is roadworthy.

Can I still drive with a failed MOT?

It is illegal to drive without an MOT certificate. If you fail your test and don't have any time left before your previous MOT's expiry date, you legally cannot drive your car. You can, however, still have it towed to a garage or an approved MOT test centre for repairs. Keep in mind you will need to have your retest at the same centre that did your first one.

Are there different levels of MOT failure?

With MOT testing, a fail is a fail. Your car is either roadworthy or it isn't. That doesn't mean all fails are created equal, however. MOT costs vary wildly depending on the type of repairs your car needs. If, for example, you fail your MOT due to a burst light bulb, you might be able to spend just a few pounds on replacements. But if your car has major mechanical problems (like severely worn-down brakes or unstable suspension, the repairs could cost hundreds or thousands of pounds.

Can I appeal an MOT fail decision?

You can appeal your MOT test failure if you think it's wrong. You'll need to fill out the complaint form here, then contact the DVSA. In the form, you will explain why you think your car is roadworthy and provide evidence (like a mechanic's report) supporting your claim.

For your complaint to be valid, you cannot alter your vehicle in any way since the test. You also must submit the form within 14 days of your test for consideration.

If the examiner agrees to your appeal, they can allow you to keep driving until you get retested. Keep in mind that this process could take weeks or even months, depending on your case's complexity.

Can I take my car to a different testing center after it fails an MOT?

Per UK law, you must take your car for retesting at the same centre that issued your first MOT certificate. This is to ensure consistency in the testing procedure and to make sure no part of it is skipped or overlooked. If you're not happy with the results of your first MOT test, you can appeal them as explained above.

Do older vehicles normally fail MOTs more frequently?

Since older cars frequently have poor exhaust emissions and begin to develop major performance issues, they tend to fail MOTs more often than newer cars. At the end of the day, it all comes down to maintenance. If you regularly service your car (especially if you own an older model), it has a much better chance of passing.

Can I get a refund for the MOT fee if my vehicle fails?

Since you pay for the service, you are not entitled to a refund if you fail your MOT. Under certain circumstances, however, you can retest your vehicle for free. And if you can't, the highest you will pay is 50% of your original MOT price (which maxes out at £54.85).

Do minor faults lead to an MOT fail?

Typically, minor faults do not lead to an MOT fail. The will instead result in an advisory notice if they are deemed dangerous and need to be fixed as soon as possible. Your tester will also make not of small flaws and potential upcoming problems, such as tyre treat that is technically legal but will need replacing soon.

That said, there is still the chance that a minor fault could lead to your car failing its MOT test. If you have enough minor faults adding up, it will affect the state of your vehicle's roadworthiness.

Can I sell my car if it fails its MOT?

You technically could sell your car without an MOT certificate. It will just be much harder to find a buyer. Research from SMMT shows us 66% of car buyers wouldn't even consider a car without one. Not having an MOT certificate will also greatly reduce your car's resale value.