Nearly a third of cars fail their MOT due to small issues that could have been picked up at home, such as a blown bulb, worn wiper blade, or empty washer bottle. That is why knowing what to check before MOT day matters. A quick 15-minute check can help you spot simple problems early, save money on a retest, and avoid failing the MOT over something that could have been fixed in minutes.
We have based this guide on the same key areas DVSA testers check during an MOT, so this is not guesswork. It is a practical MOT checklist built around the checks drivers can do themselves before booking. Used properly, it can help you catch common reasons for MOT failure before they become a problem.
The Most Common Reasons for MOT Failures
DVSA figures show that the biggest MOT problem areas are still the basics drivers deal with every day. The top failure categories are lighting and signalling, suspension, brakes, and tyres, with lights and signals making up the largest share of recorded defects. These are the parts most likely to result in a failure, even when the car feels normal on a routine drive.
Lights cause so many failures because there are several ways they can go wrong at once. A bulb may stop working properly, a lens may be damaged, or a fault may only show up when you test the full beam, brake lights, indicators, or number plate lamps together. It only takes one issue in that system for a vehicle to fail.
Suspension and brakes are high on the list because they tend to wear down gradually over time. Many drivers get used to a car that feels a bit rough over bumps or slightly unsettled when braking, but MOT testers are checking whether these parts are still in a safe, roadworthy condition. If they are not in good condition, that is often what causes the failure.
Tyres are another common problem because they are easy to ignore until the tread is close to the limit or the sidewall starts showing damage. A tyre can look acceptable at a glance and still be worn enough to fail, especially if the wear is uneven across the surface. That is one reason tyre checks are one of the most important parts of any MOT check.
DVSA data also shows that visibility problems remain an important cause of MOT failures. Faults affecting the view of the road can include worn wipers, damaged glass, or rear-view mirrors that are loose, cracked, or not giving a clear line of sight. These are not minor details in the test. They are treated as safety items because they directly affect what the driver can see and react to.
Essential Pre-MOT Checks You Can Do Yourself
These are simple checks you can do on your driveway or outside your home when your MOT is due. You do not need specialist tools, a ramp, or mechanical experience. Just give yourself 15 minutes, work around the car in order, and fix anything obvious before test day.
1. Exterior: Lights, Indicators, and Number Plates
Start with a full walk-round while the lights are switched on. Check headlights, sidelights, indicators, hazard lights, brake lights, fog lamps, and the number plate lamps.
Then look at both number plates closely. They need to be clean, easy to read, correctly spaced, and securely fixed. It is also worth checking for loose trim or any damage that has left sharp edges, especially around the bumper or number plate area.
2. Tyres and Wheels: The 20p Test
The legal minimum tread depth is 1.6mm across the central three-quarters of the tyre and around the full circumference. The easiest home check is the 20p test. Put a 20p coin into the main tread grooves in several places. If the outer rim of the coin is visible, the tyre may be too worn.
Do not stop at tread depth. Check each tyre sidewall for cuts, bulges, splits, or exposed cords, because any of those can cause a failure. Also look for obvious damage to the wheel itself, especially if the car has recently hit a kerb or pothole.
3. Windscreens, Wipers, and Screenwash
Your windscreen must not have chips or cracks larger than 10mm in the driver’s direct line of sight, or larger than 40mm anywhere else in the swept area. Even a smaller mark can become a bigger problem if it sits where the wipers pass and affects visibility.
Check that the blades clear the glass cleanly and do not leave smears or missed patches. Torn rubber, dragging blades, or an empty washer bottle are easy to miss, but they can still be an MOT issue because they affect your view of the road.
4. Interior: Dashboard Warning Lights and Controls
Turn the ignition on and watch the dashboard. Warning lights usually come on briefly and then go out. If the engine management, ABS, airbag, or brake warning light stays on, that needs sorting before the test.
Press the horn to make sure it gives one steady, continuous tone. Pull each seatbelt sharply to check that it locks, make sure it clicks into place properly, and confirm it retracts without slack. While you are in the driver’s seat, make sure the steering wheel feels secure and normal in use, not loose or unusually resistant.
5. Under the Bonnet: Fluid Levels and Battery
Park on level ground before checking fluids. Engine oil should sit between the minimum and maximum marks on the dipstick, coolant should be within the marked range, and brake fluid should not be low. If fluid levels are very low, the car may not be in a suitable condition for testing, so it is worth checking them before the appointment.
Have a quick look around for obvious leaks, damp patches, or a strong smell from the fuel system. Then check the battery is firmly secured and that the terminals are not heavily corroded. A loose battery is a simple problem, but it is still one worth fixing before the car goes in.
Review Your Vehicle’s MOT History Before Testing
One of the smartest things you can do before booking the test is look back at the car’s previous MOT results. A past advisory is often the earliest warning sign of what may fail next time. If the same issue has appeared more than once, there is a good chance it has worsened rather than disappeared on its own.
This is where an MOT history check becomes more useful than a quick walk-around. It helps you spot repeat patterns such as tyre wear, corrosion, brake wear, or advisories linked to the exhaust system or the driver's view. That gives you a more focused list of what to inspect before the car goes for its test, instead of guessing where the risk might be.
For example, if last year’s MOT mentioned tyres close to the limit and a minor visibility issue, those are the areas to check first this year. If brake wear was flagged in two MOTs in a row, that is a stronger sign of an ongoing issue than a one-off advisory. The value is not just in seeing whether the car passed or failed. It is in seeing what has been developing over time.
If you want a quick starting point, run a free MOT history check before your appointment. If you want a more complete picture before you spend money on repairs or commit to a vehicle, a more comprehensive vehicle check can help you review its testing record alongside other useful details in one place.
A BHP check can also be useful if you want to confirm key performance details for the vehicle alongside its MOT and history records. If you drive into clean air zones, a ULEZ checker can help you see whether the vehicle meets the required emissions standard before you book, buy, or budget for running costs.
What Will the MOT Tester Check at the Garage?
The checks you can do at home are useful, but they only cover what you can see and test safely on your own. At the garage, the MOT tester will carry out a deeper inspection using equipment you are unlikely to have access to at home. That is the point where hidden wear, looseness, or corrosion often gets picked up.
A tester will usually raise the car on a ramp so they can inspect the underside properly. This allows them to examine suspension components, steering joints, brake lines, mountings, and structural areas that are hard to judge from ground level. They look for wear, damage, leaks, looseness, and corrosion in places most drivers never get a clear view of.
They will also check parts of the car that can only be assessed properly with the right equipment or in a proper test setting. This includes measuring emissions, checking that parts underneath the car are in good condition and securely fitted, and spotting wear or movement in the steering and suspension that you might not notice in everyday driving. A car can feel mostly fine on the road and still have enough wear underneath to cause a fail.
This is also why a clean DIY check does not guarantee a pass. You might spot an obvious bulb or wiper issue yourself, but you cannot fully assess suspension movement, braking balance, or hidden rust around load-bearing areas without the car being inspected properly. The home check helps reduce avoidable problems. The garage check is there to confirm the car still meets the standard where it matters most.
Frequently Asked Questions
Can a dirty car fail an MOT?
Not by itself. Dirt is not a test defect in the same way as a faulty light or worn tyre. But a tester can refuse to carry out the MOT if the vehicle, or any part of it, is so dirty that inspection is unreasonably difficult. That can include a boot packed with clutter blocking access, or heavy mud underneath that stops proper examination.
Try to make the car easy to inspect. Clear out the boot, remove anything covering access points, and do a basic wash if the body or underside is heavily soiled. That will not improve the result on its own, but it can prevent an avoidable refusal to test.
Can I drive my vehicle away if it fails?
You can only drive it away if your current MOT is still valid and the failure did not include any dangerous defects. If a dangerous problem is listed, the car must be repaired before it is driven. Even where you are allowed to take it away, it still has to be roadworthy.
There is no MOT grace period after a failure. If the old MOT has already expired, rules around driving without an MOT still apply, and the normal exception is only for travel to or from a pre-arranged MOT test or a place of repair. If you drive a car with a dangerous defect, you can face a fine of up to £2,500, 3 penalty points, and a possible driving ban.
Can you insure a car without an MOT?
Yes, in some cases you can insure a car without an MOT, because insurance and MOT are separate things. But having insurance does not automatically make the car legal to drive. In the UK, if the car needs an MOT and does not have one, you can still face penalties for using it on the road.
According to GOV.UK, driving without a valid MOT can lead to a fine of up to £1,000.
- Important: insurance may exist on paper, but a missing MOT can still create problems if the car is unroadworthy or if you need to make a claim.
Can you tax a vehicle without an MOT?
Usually, no. In most cases, you cannot tax a vehicle without an MOT if that vehicle is old enough to need one. According to GOV.UK, you need evidence of a current MOT when taxing a vehicle if the vehicle requires an MOT. The main exceptions are vehicles that are exempt from MOT rules, such as newer vehicles that are not yet due their first test or certain historic vehicles.
If the car needs an MOT, the MOT usually comes before the tax. So if your MOT has expired, the normal next step is to book the test first, not try to renew the tax first. Once the MOT record updates, you can usually move on with taxing the vehicle, provided there are no exemption issues.
