The Ministry of Transport test (MOT) is one of several tests car owners in the United Kingdom must pass for vehicles to remain legally on the roads. The test covers several areas, including brakes, steering and suspension, lights, and exhaust emissions. However, a number plate can also cause an MOT test to fail.

Car owners must pay MOT fees, so failing the test can be expensive. Many drivers are unaware that even a seemingly minor infringement, such as an incorrectly sized number plate, can cause a failed MOT test. How can you avoid this?

What Is an MOT Test?

The MOT test checks essential elements of vehicles to ensure that they meet legal standards. Some may think it’s the same as having cars serviced or a general mechanical inspection. However, the test focuses more on a car’s safety and anti-pollution aspects. It ensures that car owners know their responsibilities and that their vehicle is safe to drive.

MOT tests check the following car parts:

  • Lights
  • Electrical wiring and battery
  • Windscreen
  • Wipers or washers
  • Steering and suspension
  • Seatbelts
  • Fuel system
  • Vehicle body
  • Seats
  • Tailgates
  • Towbars
  • Exhaust emission
  • Doors
  • Mirrors
  • Exhaust system
  • Horn
  • Brakes
  • Tyres, wheels, and TPMS
  • Bonnet
  • Registration plates

The test doesn’t cover the condition of engines, clutches, and gearboxes. Generally, car owners must ensure that vehicles are in good condition upon taking an MOT test. Should there be any deficiencies, it could result in a failed test.

Number Plate Reasons for Failing an MOT Test

Yes, even if the other items on your car meet the legal requirements, a faulty number plate can still cause an MOT test to fail. You may think that number plates aren’t something to be overly concerned about, but having one that doesn’t comply with the regulations can be just as serious a problem as any other item on the list.

So, what can cause a number plate to fail an MOT test? First of all, the number plate must adhere to strict rules. BS AU 145e is the UK’s standard all cars and owners must follow. If your number plate has any of the following during an MOT, you will most probably have your car registered as an MOT failure:


All number plates in the UK must be in good condition and readable. They go through tests that ensure they’re strong and secure. Number plates must be resistant to impacts and elements such as the sun and rain, for instance. If any signs of damage, such as scratches, dents, or fading, make the numbers difficult to read, you will fail the MOT.


Number plates must also be clean and clear of dirt, grime, and debris. If any of these things are present on the number plate and impair visibility, you’ll fail your MOT. As a car owner, it’s your responsibility to ensure that the number plate on your car is always clean and legible.

Dysfunctional Light

All number plates must be reflective enough to be read in darkness. Rear number plates must have a small light fixture to illuminate plate numbers to other drivers. If the light is broken or malfunctioning, it could be enough for the MOT examiner to fail you.


Yes, your number plates must be securely attached to the car. However, plate numbers held on by adhesive tapes or glue will result in a failed MOT. Stuck-on number plates aren’t secure enough, so ensure that your plates are firmly attached to the car and won’t cause a distraction on the roads.


It’s possible to get number plates from various unregulated sources, which can be illegal. These could be customised plates with too large or small characters or even plastic plates. All number plates must adhere to the UK standard as noted above otherwise.


Of course, not having a number plate at all will also result in a failed MOT. It’s illegal to drive a car without a number plate in the UK, so check yours before taking an MOT test.

Secure Number Plates With Show Plates World

In the UK, number plates are regulated, and only a few companies are approved to make them. Show Plates World is one of the country’s top-rated and trusted number plate makers. All our plates comply with the BS AU 145e regulations and are made of high-quality reflective materials. We also guarantee car owners secure delivery of the plates and provide installation advice.

Show Plates World understands how integral the MOT tests are for car owners, so we make sure that our plates will tick all the necessary boxes during the test. With our services, you can be sure that you won’t have any problems with your number plates regarding the MOT test.

Let us help you be 100% sure with one part of your MOT test and eliminate the hassle of getting number plates. Contact us today!