Can a Number Plate Fail an MOT? Faded, Cracked and Illegal Plates Explained

Short answer: a number plate MOT fail is more common than you’d think. Yes, plates can fail. If a plate is missing, loose, faded or cracked so it’s hard to read, showing the wrong registration, or not made to the legal standard (wrong font, spacing or markings), it’s a major defect and the car fails. A broken number plate light is also a fail. Most of these are cheap and quick to fix before the test.

Number plates sound like the last thing to fail an MOT on. They’re not. DVSA figures for 2025, analysed by Green Flag, show more than 1.3 million MOT failure items linked to number plates and their lights on cars and light vans in a single year.

Written by the PlateBoss team, led by owner HD. We’ve been making plates since 2019 and are a DVLA-registered number plate supplier with a workshop in Hounslow, west London. Checked against DVSA, DVLA and GOV.UK guidance, September 2026. How we write our guides.

In this guide

• What the MOT checks on your number plates
• The most common number plate MOT fails
• Faded, cracked and peeling plates
• 3D, 4D and “custom” plates
• The number plate light
• A 2-minute check before your MOT
• What to do if your plates failed
• FAQs

What the MOT checks on your number plates

The MOT inspection manual lists four number plate problems, and every one of them is a major defect, which means an automatic fail:

• The plate is missing, or so insecure it’s likely to fall off.
• The registration is missing or illegible.
• The plate shows an incorrect registration.
• The plate doesn’t conform to the specified requirements, such as the wrong font, character size, spacing, background or markings.

The tester also checks the number plate lamp, which has its own section of the MOT (more on that below).

The most common number plate MOT fails

Green Flag’s analysis of DVSA data for 2025 (class 4 vehicles, which is most cars and light vans) gives a clear picture of what actually goes wrong:

Illegible plates are the big one after lights. That’s usually an old plate that’s faded, cracked or delaminating, rather than a dirty one.

What we see at the workshop

We get a steady stream of customers coming to our Hounslow workshop straight from a failed MOT. Most of them have cracked or damaged plates: a split across the rear plate, a corner broken off from a knock, or a front plate that has come loose. But more and more of them now have illegally spaced plates, where the characters have been moved to spell a name or a word. That’s often a set bought online years ago that passed a few MOTs before a tester finally picked it up.

The fix is the same either way: a new plate made to the legal standard, usually while they wait, so they can go straight back to the garage.

Faded, cracked and peeling plates

Plates don’t last forever. Years of sun, jet washes and stone chips take their toll, and the rear plate usually goes first. Watch for:

• Fading: black characters turning grey, or the yellow going pale and patchy.
• Delamination: the clear front layer lifting and clouding, often starting at the edges or around screw holes.
• Cracks and damage: especially across a character, from a screw hole, or a corner knocked off in a car park. This is the number one reason MOT-fail customers come to us.
• Lost reflectivity: the plate no longer “lights up” when you shine a torch on it at night.

If the registration is hard to read, cleaning won’t save it. The fix is a new plate. See our guide on how to clean number plates for plates that are just grubby.

3D, 4D and “custom” plates at the MOT

Raised 3D gel and 4D plates are legal and will pass, as long as they’re made to BS AU 145e: solid black characters, the Charles Wright font, the correct size and spacing, and the supplier’s name, postcode and BS AU 145e mark on the plate. We explain it in full in are 4D plates legal?

What fails are the “custom” touches: italic or stylised fonts, moved spacing on a private reg, carbon or two-tone letters, and plates with no supplier markings. Those fall under “doesn’t conform to the specified requirements”. They’re usually show plates bought online without any documents being checked.

The number plate light

Number plate lamp problems cause more MOT fails than the plates themselves. It’s a major defect if the only lamp doesn’t work, all the lamps are out, or the lamp doesn’t come on with the sidelights. If you have two lamps and one is out, it’s a minor defect: it goes on the certificate, but it won’t fail on its own. The bulb is usually a cheap, five-minute fix.

A 2-minute number plate check before your MOT

1. Read it from 20 metres. If any character is hard to make out, it’s a risk.
2. Push each corner. Nothing should move, rattle or lift.
3. Look for cracks and cloudy edges, especially on the rear plate.
4. Check the markings: the supplier’s name and postcode, and BS AU 145e, along the bottom.
5. Turn on the sidelights and check the rear plate is lit.
6. Remove anything covering it: tinted covers, bike racks, stickers or dirt.

What to do if your number plates failed the MOT

A number plate MOT fail is one of the easiest to put right. Get the right plates made and fitted, then take the car back for the retest. You’ll need your ID and V5C to get new plates from a registered supplier. Here’s the full list of documents needed for number plates. Fitting takes a few minutes with pads or screws, and our fitting guide shows you how.

If you’re near Hounslow, it’s often quickest to come to us: we can make a standard set while you wait, so you can be back at the garage the same day.

Replacement plates that pass the MOT

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Replacement Number Plates

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3D Gel Number Plates

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£70.00 Original price was: £70.00.£49.99Current price is: £49.99.

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4D 3mm Number Plates

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£70.00 Original price was: £70.00.£49.99Current price is: £49.99.

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Extra Strong Adhesive Pads (8 in a pack)

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Could number plate penalties get tougher?

Possibly. The Department for Transport consulted in 2026 on adding penalty points, and powers to seize vehicles, for driving with an incorrect, altered or false number plate. The consultation closed on 11 May 2026, and no decision had been announced at the time of writing. For now, the penalty is a fine of up to £1,000 and an MOT fail.

Number plate MOT fail: FAQs

Sources

• Aviva / Green Flag: More than 1.3 million MOT failures linked to number plate defects (DVSA data, 2025)
• GOV.UK: Displaying number plates
• GOV.UK: Rules for number plates
• UK Parliament: written answer on the number plate penalties consultation