Your number plates are checked at every MOT, and they’re one of the most avoidable reasons to fail. The tester looks at the plates themselves, how they’re fixed, and the light that illuminates the rear plate. Here’s what they check and what fails.
In this guide
What the MOT checks
Testers look at whether each plate:
- is present, secure and not likely to fall off
- is in good condition – not cracked, delaminating or faded
- has the right colours: black on white at the front, black on yellow at the rear
- uses correctly formed and spaced characters that can’t easily be misread
- isn’t obscured by a tow bar, bike rack, dirt or a cover
- has a working rear number plate light
The 9 most common number plate failures
1. Incorrect spacing
Closing the gap or moving it to spell a name is a straight fail. See number plate spacing rules.
2. The wrong font
Italic, stylised or bold characters fail. Only the Charles Wright 2001 typeface is legal – see the legal number plate font.
3. Coloured or two-tone characters
Characters must be black. Two-tone “3D effect” printing and coloured 4D characters fail on plates made since September 2021.
4. Patterned backgrounds
Carbon, honeycomb or picture backgrounds aren’t allowed behind the characters.
5. Cracked, faded or peeling plates
Old plates crack around fixing holes and their reflective layer fades or peels. A plate that’s hard to read fails. Replacing them is quick – see replacing damaged plates.
6. Loose or missing plates
A plate held by one screw or flapping on worn sticky pads will fail. Our fitting guide shows the secure options.
7. Screw heads altering characters
A screw through the middle of a character – or a cap that turns an I into a T – can change how the registration reads.
8. Obscured plates
Tow bars, cycle carriers and towing balls that block the rear plate fail unless you fit a legal plate to the carrier.
9. Broken plate light
The rear plate must be lit at night. A blown bulb is a fail, and it’s one of the cheapest things to fix.
Do 3D and 4D plates pass the MOT?
Yes, if they’re made legally. Raised characters are allowed under BS AU 145e. What fails is the wrong font, colour, spacing or an unmarked plate. Read are 3D and 4D number plates legal?
A two-minute pre-MOT plate check
- Both plates present, clean and firmly fixed
- White front, yellow rear, black characters
- Correct spacing between the two groups
- No cracks, peeling or fading
- Supplier name, postcode and BS AU 145e along the bottom
- Rear plate light working
Fail-proof replacement plates
Order road-legal plates made to BS AU 145e before your MOT. We dispatch fast.
Frequently asked questions
Is a number plate MOT failure a major or minor defect?
Plate defects that affect legibility or security are usually recorded as major, which means a fail until the plates are fixed.
Will my MOT fail if my plates don’t have the BS AU 145e mark?
Plates fitted before September 2021 can show the older BS AU 145d mark. New plates without a valid mark and supplier details shouldn’t be fitted at all.
Can a dirty number plate fail an MOT?
Yes, if the tester can’t read it. Clean your plates before the test.
How quickly can I get replacement plates before my MOT?
Order with your documents uploaded at checkout and we can make your plates straight away. See our delivery page for dispatch times.
