What Can Fail an MOT? 3 Things to Check Before Your Test

Yes. Headlamp aim outside the permitted limits can result in a major defect. For most cars and light vans, tyres need at least 1.6mm of tread across the central three-quarters of the tyre and around its entire circumference. Required wipers must also clear the windscreen sufficiently to give the driver an adequate view.

These are only three parts of a much wider MOT inspection, but they are useful checks to make before your test.

1. Misaligned Headlights

It is not enough for your headlights simply to switch on. Their alignment, or headlamp aim, is also assessed during an MOT.

Headlights need to illuminate the road correctly without the beam being incorrectly positioned. Headlamp aim outside the limits set by the DVSA is classed as a major defect.

Before your MOT, check that both headlights work and look for obvious damage or a lamp that appears loose or noticeably out of position.

Accurate alignment requires suitable testing equipment, so avoid randomly adjusting the headlights yourself if you suspect there is a problem.

2. Tyre Tread Depth Below 1.6mm

For most cars and light vans, the legal minimum tyre tread depth is 1.6mm across the central three-quarters of the tyre and around its entire circumference.

Check all four tyres rather than looking at just one section, as tyres can wear unevenly. You should also look for obvious damage, as tread depth is not the only aspect of tyre condition considered during an MOT.

If you are unsure whether your tyres are suitable for the road, having them professionally inspected is better than guessing. JNCC can also help if you need new tyres fitted in Warwick.

3. Wiper Blades Not Clearing the Windscreen

Wiper blades deteriorate gradually, so it is easy to become accustomed to streaking or poor performance.

During an MOT, required wipers need to work effectively enough to provide an adequate view through the windscreen. A required wiper that is missing or clearly fails to clear the windscreen can result in a major defect.

Before your test, operate your washers and wipers and look for:

• Areas of the windscreen left uncleared
• Persistent smearing that affects visibility
• Split or damaged wiper blades
• Wipers that do not operate properly
• Washer jets that do not provide enough fluid

Remember to check your washer fluid too. The washer system must provide enough fluid for the wipers to clear the windscreen effectively.

What Else Can Fail an MOT?

Headlights, tyres and wipers are only part of the test. An MOT also examines areas including:

• Brakes
• Steering
• Suspension
• Vehicle structure
• Seat belts
• Lights and electrical equipment
• Exhaust and emissions
• Visibility

You can find the complete testing requirements here.

For more information about the test itself, read JNCC’s MOT FAQs.

Your Number Plate Can Affect Your MOT Too

One easy-to-miss MOT check is the condition and visibility of your registration plates. A number plate can cause problems if it is missing, insecure, incorrectly displayed or so dirty or damaged that the registration cannot be read properly.

Before your MOT, take a quick look at both plates. Make sure they are secure, clearly legible and not obscured by dirt. The MOT also checks whether mandatory registration plate lamps operate correctly where required.

It is a particularly simple pre-MOT check because you do not need specialist equipment to spot an obviously loose, damaged or unreadable plate.

If a replacement is needed, Just Nice Clean Cars also provides replacement number plates.

Why Small MOT Problems Are Worth Checking Early

Some MOT issues can develop gradually, which means you may not notice them during everyday driving. Wiper blades can slowly become less effective, tyre tread wears down over time, and headlight alignment may change without an obvious warning.

Checking your vehicle before its MOT gives you an opportunity to spot these simpler problems rather than discovering them for the first time during the test.

It is also worth remembering that passing an MOT does not mean your vehicle will remain roadworthy until the next one. Regular maintenance and acting on signs of wear can help keep your car safe between annual tests.

Quick Checks Before Your MOT

A few minutes before test day can help you identify straightforward problems. Check that your lights work, inspect your tyres, test your washers and wipers, and make sure your view through the windscreen is clear.

These checks cannot guarantee a pass, but they may help you catch simple issues before your appointment. Remember that an MOT is a minimum roadworthiness assessment of your vehicle at the time of the test. It confirms that your vehicle met the required standards when it was tested, but it does not guarantee that it will remain roadworthy until your next MOT.

Your vehicle is in constant use, so wear, faults or other issues can develop at any time – even within days of passing an MOT – and these may not have been present or possible to anticipate during the test. Regular maintenance, servicing and acting promptly on signs of wear or changes in how your vehicle feels can help keep it safe and roadworthy between annual MOT tests.

Frequently Asked Questions About MOT Failures

Can Misaligned Headlights Fail an MOT?

Yes. Headlamp aim outside the permitted limits is categorised as a major defect.

Will Tyres Below 1.6mm Fail an MOT?

Yes, where a tyre does not meet the applicable legal tread-depth requirement. For most cars and light vans, this means at least 1.6mm across the central three-quarters and around the entire circumference.

Can Wiper Blades Cause an MOT Failure?

Yes. If a required wiper is missing or clearly fails to clear the windscreen sufficiently, it can result in a major defect.

Can an Empty Washer Bottle Cause an MOT Failure?

Yes. If the washer system does not provide sufficient fluid to clear the windscreen effectively, this can result in a major defect.

Is Your MOT Due?

Not sure when your MOT is due? You can check when your MOT is due using the official DVSA MOT checker on GOV.UK.

If your test is approaching, checking your headlights, tyres and wipers before your appointment can help identify some of the simpler problems that may affect an MOT result.

If your MOT is due, you can book an MOT with Just Nice Clean Cars in Warwick. The team will carry out the test and explain clearly if your vehicle needs any attention.

Have a question before booking your MOT? Chat with our Warwick team on WhatsApp.