What can fail an MOT?

The most common causes of MOT failure

The Driver and Vehicle Standards Agency (DVSA) reports that up to a third of all UK vehicles fail the annual MOT test each year  many for minor issues that could've easily been prevented.

The MOT test includes several checks, ranging from your tyres to your headlights.


Faulty or broken lights are a common cause of MOT failure. Luckily, they’re also one of the easiest parts of your vehicle to check yourself before your MOT.

Test your headlights, fog lights, brake lights, number plate lamps, rear lights, indicators and hazard lights to make sure they’re in good working order and that no bulbs need replacing. Also check that your lights aren’t covered or obscured by stickers.

Lights can also cause an MOT fail for other reasons:

  • Brightness - the bulb in your lights must emit more than 50% of its potential brightness to pass the MOT. That said, if your headlights are too bright or poorly adjusted this can also result in MOT failure as they could dazzle other drivers.
  • Indicator speed - if an indicator flashes less than 60 times a minute, this is an MOT fail. Indicators should flash between 60 and 120 times a minute.
  • Faulty brake lights - check your brake lights are working and make sure they don’t stay on once the brake pedal is released. Ask a friend or family member to help with this one by getting them to look at your lights as you apply the brake.

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Car suspension issues aren’t always easy to spot as the suspension system isn't something most drivers can check themselves.

However, you might notice issues while driving that can indicate suspension problems:

  • Bumps - if you’re starting to feel every bump in the road, or your car sometimes jerks on uneven road surfaces, your vehicle’s suspension might need attention.
  • Turning - experiencing a drift or pull while driving might suggest that your vehicle’s shock absorbers have worn out. Shock absorbers are an important part of your suspension as they keep the vehicle balanced against the force of a turn.
  • Tyre tread - if you start to notice uneven tyre tread across the same axis, this could mean that your suspension is uneven.
  • Dipping - if your car dips forward when you brake firmly, your shock absorbers could be worn out.

If you’re experiencing any of these issues, get your car checked by a garage before your MOT to avoid a fail.


Brakes are essential for road safety, so brake discs and pads are checked thoroughly as part of the MOT test.

If a technician notices the brake pads are wearing thin but the car is still safe to drive, this will be flagged as an Advisory note on your certificate. This means you should get them fixed at a later date.

Juddering when you brake is a tell-tale sign that there’s an issue with your brakes - get them checked by a garage before your MOT test.


Tyres tend to be a common cause of MOT failure for several reasons:

  • Tread - the minimum legal tyre tread depth for cars and vans is 1.6mm in a continuous band around the central 3/4 of the tyre. Any tyres with a tread of less than 1.6mm will be marked as an MOT fail. Be aware that not all new tyres come with the same tread depth - they can vary from 7-10mm.
  • Damage - if the tyre contains any cuts, or the ply or cords (the inside of the tyre) are exposed, your car is likely to fail. Look out for any bulges, lumps or tears, as these also mean the tyre’s structural integrity is compromised and will therefore lead to MOT failure.
  • Sizing - if a tyre is of a different size to the partner tyre on the same axis, the car is likely to fail. You must also ensure every tyre diameter matches the manufacturer specification.

MOT tests from the AA

When you book an MOT test with Smart Care, you get:

  • Free vehicle collection and return.
  • AA approved garages.
  • Quick and easy online booking and payment.
  • 12-month guarantee on all parts and labour.
  • Fair, transparent pricing.

And if your car fails its MOT and you’d like us to make the necessary repairs, we’ll carry out your retest for free. In some locations we even have next-day availability for servicing and MOTs.

AA approved MOTs, services and repairs at a local garage near you

Book with Smart Care and get a 12-month guarantee on all parts and labour, fixed pricing with no hidden extras and free vehicle collection and return (subject to availability).