11th May 2023

What causes your car to fail its MOT?

What causes your car to fail its MOT? The most common reasons explained


All vehicles aged three years or over require an annual MOT test, as legally enforced by The Vehicle Standards Agency (DVSA). The test can cause driver anxiety, as it’s inevitably a ‘pass or fail’ scenario. To help this, we’ve compiled a guide based on the main reasons why your car can fail its MOT.  

‘As part of JDM customer service, should your car fail its MOT, we will happily re-test your vehicle free of charge within 10 working days’.

MOT myths

Over the decades, we’ve strived to dispel the many MOT myths that you as car owners are subjected to. Our most heard myth is that one of the windows not fully opening would cause your car to fail. This is not true.

However, with there being so much misinformation out there, we can totally understand why MOTs can feel like a minefield. Maintaining a good condition within your vehicle can feel like an unenviable task.

The most common reasons your car may fail its MOT

According to the UK Government, almost 50% of all vehicle failures could be avoided by regular vehicle owner maintenance and checks. Surprisingly to most drivers, the most common reasons for MOT failure are:

  • Vehicle lights
  • Suspension and tyres condition
  • Brakes
  • ‘Driver’s view of the road’ obstructions, such as mirrors, wipers and washers

Vehicle lights

Whether it be as simple as a blown bulb, or indicators not functioning properly, vehicle lights are the number one main cause for vehicle MOT failures. There are simple steps you can take, to ensure your lights are in complete working order.

Walk around your car, prior to your MOT, with each light switched on and manually check they work. Ask somebody to help with this, or park against a reflective surface to check your brake lights. Don’t forget to check less considered lights too, such as the registration number plate light, as well as your indicators.

If you notice that any of your lights are not working, please let us know prior to the MOT, if we have time we can often change these for you before beginning the MOT Test. Bulbs are fitted free of charge.

Suspension and braking systems can cause your car to fail its MOT

Around 20% of all MOT test fail due to suspension-related issues. It is typically one of the more expensive issues to fix, so being aware of the warning signs is key to avoiding this.

Most suspension issues start with a snapped spring, or a leak within the shock absorber, so can easily go unnoticed to most vehicle owners.

The best preventative steps you can take over your suspension is by listening to the noises created by your vehicle. Do you hear any unusual clunk sounds or feel any strange sensations? Check the levelling of your car – does it feel level on both sides? Try to push down each corner and check for a ‘bouncing’ reaction when you let go of the vehicle.

Don’t forget as part of your suspension, your tyres on both the front and rear also must be checked (in terms of size, condition and tread depth).

Obstructions to the driver’s view

As a driver, obstructions can be something that easily go unnoticed. This is because you’re used to your windscreen being your most seen views throughout any given journey and tend not to recognise potential obstructions, as you may have become used to them. It’s worth noting that obstructions to your rear view are not checked during an MOT test.

Obstructions include:

  • Windscreen blocks, such as air fresheners, satellite navigation systems
  • The use of stickers or logos and advertisements
  • Cracks or chips affecting the eyeline.
  • The overall condition of mirrors – ensuring they are regularly cleaned and cleared

A guide to vehicle obscuration provides more detailed clarity and examples of this.

Our MOT promise to you – why choose us for your MOT test?

There are many reasons why you should consider your next MOT Test with John Delany Motors. We are proud to declare that each of our technicians is fully skilled and highly trained. We take incredible care to ensure that each job we undertake is completed with the utmost efficiency at the most reasonable price to our customers.

Our MOT tests also come with our guarantee of a completely free re-test, should your vehicle fail the test. We always keep you informed every step of the way and will never complete any work without your prior knowledge and consent.

If you are left with further unanswered questions, feel free to read our MOT FAQ page. 

For those drivers who now feel confident with the A-Z of MOTs, feel free to spend some time taking the MOT quiz
Give us a call and get your vehicle booked in with us very soon.