These 5 surprising things could make your car fail its MOT

While many drivers are familiar with the more common reasons for failing an MOT, such as faulty brakes or worn tyres, there are several lesser-known issues that can result in a disappointing outcome during your vehicle's annual inspection. 

From hanging fluffy dice to an empty washer fluid tank, we reveal the unsuspecting culprits that could thwart your car's chances of passing an MOT, and how you can safely avoid them.

Looking to go electric, but on a tight budget? Check out our guide to the cheapest electric cars

1. Accessories in the rear view mirror

The Highway Code states that drivers should be 'free from obstructions to vision', so any item that gets in the way of the driver's field of view could warrant a fail. This includes sat navs, dash cams, phone holders, air fresheners, stickers and even a fluffy dice decoration.

That's not to say you can't ever put your sat nav or phone holder on your windscreen - but you must do so safely and without obstructing the view of the road.

While the Driver and Vehicle Standards Agency (DVSA) states that MOT assessors are allowed to remove items such as sat navs and air fresheners when undertaking a test, they must inform the driver that they have done so. If the obstruction cannot be removed, this may result in a fail.

It's best to err on the side of caution before an MOT test and keep your windscreen dash as clutter-free as possible. If you need a sat nav or phone holder for navigation, look for one which can be attached to the air vents instead of the windscreen.

2. Not enough windscreen fluid

Most drivers know that having functional wipers is essential for an MOT, but don't forget about the wiper fluid.

According to guidance from the DVSA, 'washers must provide enough fluid for the wipers to clear the windscreen effectively'.

If your car arrives to be assessed and there is insufficient fluid in the car, this can result in an MOT failure. This is because you need to be able to keep your windscreen clear when you're driving, as a build-up of dirt will obscure your view of the road.

Some garages may offer to fill the fluid up for you, but this isn't always the case. Ensure you always have the windscreen washer fluid levels topped up, especially before heading to an MOT.

3. Non-standard number plates

MOT rules state that number plates are the first thing an assessor should inspect.

The DVSA says that plates must not:

• be obscured, excessively damaged, deteriorated or delaminated
• have background overprinting
• have any feature or fixing that has the effect of changing the appearance or legibility of any of the letters
• have a honeycomb or similar effect background on vehicles first registered on or after 1 September 2001

Any of the above could be classed as a major defect, and therefore lead to an MOT failure.

Your number plate also needs to be securely attached to the car, with the characters clear and legible.

The British Number Plate Manufacturers Association states that MOT assessors should pay attention to the position of fixing screws and bolts, and any delamination on the number plate.  

4. Incorrect headlight alignment

Headlights can make or break a successful MOT test, with broken bulbs or casings and other electrical issues being enough to cause a fail. But you might not be aware that headlights that are working but misaligned can also cause a failure.

Your headlights need to be aligned in what's often referred to as the 'Goldilocks zone': not so far down you can't see the road clearly in the dark, but not so high up that you're constantly dazzling oncoming traffic.

Headlight misalignment can often be overlooked, especially in newer, hi-tech cars where it can be adjusted with the touch of a button. One inadvertent knock could send your headlights out of whack without you even realising it.

Are night driving glasses safe to wear?

5. An extremely dirty or messy car

An untidy car is very unlikely to cause a fail, but if your car is dirty to the point of causing a safety issue the assessor may have no option.

Inside the car, this might include having a lot of rubbish in the footwells - especially under the driver's seat - which could roll under the pedals and stop them from working effectively.

The outside of the car needs to be in reasonable condition too. Having heavy dirt and grime which obscures the headlights or number plates could warrant an MOT fail.

The RAC says that if your car is excessively dirty, the examiner can refuse to carry out the MOT altogether.

To be on the safe side, clean your car before sending it to be tested. We have advice on safely cleaning your car with a pressure washer, otherwise you can wash it by hand. We don't recommend using a car wash - you can find out why in our guide: six mistakes to avoid when washing your car (and what to do instead).

If you want to give your car a bigger spruce up, take a look at the best car scratch removers from our tests. 

Find a Which? endorsed garage for your car's next MOT

Whether you're sending your car for an MOT, service or repair, you'll want to know the garage undertaking the work is trustworthy. 

The Which? Trusted Traders endorsement is only awarded to traders who have the highest standards in their field, and have passed our thorough checks and assessments.

Use the free tool below to find nearby mechanics with our seal of approval, or head to our dedicated guides on finding a reputable trader and finding a good garage.

MOTs: your questions answered

We've answered some of the most common MOT questions below, but you can find out more in our full guide on how to pass an MOT test.

How long does an MOT take?

An MOT test usually takes between 45 minutes and one hour.

When is my MOT due?

The DVSA says you can get an MOT up to a month (minus a day) before it runs out while keeping the same renewal date. For example, if your MOT runs out on 15 May, the earliest you can get an MOT to keep the same renewal date for the next year is 16 April.

If you're worried about forgetting about your MOT until it's too late, you can sign up for free text or email reminders from the DVSA.

How long does an MOT last?

An MOT lasts for 12 months. You can check your renewal date by looking for your MOT history online, or by checking the date that's printed on your current MOT certificate.

You can check the MOT status of a vehicle using this free Gov.uk tool.

Can you tax a car without an MOT?

Most cars cannot be taxed without a valid MOT.

The RAC says it is an offence to drive on a public UK road without road tax, unless you are driving your car to a pre-booked MOT test.

Drive smarter and cut your costs. Sign up for our Cars newsletter, it's free monthly