The small lamp that illuminates the rear number plate isn't lighting. If a plate has two lamps and one is out, it's still recorded. It's one of the most common and cheapest MOT failures there is — and one almost nobody notices, because you can't see it from the driver's seat.
Wording as it commonly appears on an MOT certificate: “Registration plate lamp not working”.
What does it mean?
The small lamp that illuminates the rear number plate isn't lighting. If a plate has two lamps and one is out, it's still recorded. It's one of the most common and cheapest MOT failures there is — and one almost nobody notices, because you can't see it from the driver's seat.
How serious is it?
Usually recorded as: Minor. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- A blown festoon or capless bulb
- Water in the lamp unit corroding the contacts, which is very common on hatchbacks and vans
- A cracked lens letting the weather in
- An aftermarket LED unit that has failed or was never wired correctly
What a mechanic would check
Sidelights on, then walk to the back of the car — that's the whole test. If the bulb is good I check the holder for green corrosion and the earth, because on a lot of cars it's the earth in the boot lid loom that has broken, not the bulb.
What might need replacing
- A bulb
- A plate lamp unit
- Cleaning up corroded contacts or repairing an earth
Can you still drive it?
Perfectly safe to drive, but it's a fixed-penalty offence in its own right and it fails the MOT every time. Check it whenever you check your other bulbs.
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This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.