Quick answer
A reverse light can fail MOT if it does not illuminate when reverse gear is selected, shows the wrong colour, is insecure, damaged or affected by wiring faults.
The fault is often a bulb, fuse, switch or wiring issue.
When reverse lights can fail MOT
Light not working
The reversing lamp does not illuminate when reverse is selected.
Wrong colour
Reverse lights should show the correct white light.
Damaged lens
Cracked or missing lenses can affect light output.
Loose lamp unit
Rear lamp units should be secure.
Stays on constantly
Reverse lights should not remain on when not reversing.
Intermittent fault
Lights that flicker or work only sometimes can cause issues.
Common causes of reverse light faults
Common causes include blown bulbs, faulty reverse light switches, damaged wiring, poor earth connections, corrosion or water inside the rear light unit.
On some cars, the reverse light switch is fitted to the gearbox. If the bulb is fine but the light never comes on, the switch may need checking.
What to check before the MOT
1. Select reverse safely
With the ignition on and car secure, check whether the reverse lamp lights up.
2. Use a helper
Ask someone to stand behind the car while you select reverse safely.
3. Check bulb or LED unit
Replace failed bulbs or inspect LED lamp units.
4. Inspect lens condition
Look for cracks, water ingress or missing plastic.
5. Check if it stays on
Reverse lights should switch off when reverse is deselected.
6. Investigate wiring
If bulbs are fine, wiring or switch faults may be involved.
Usually a simple repair
Many reverse light faults are simple, especially if the cause is a bulb or dirty connector.
If the reverse switch or wiring is faulty, diagnosis may take longer but should still be fixed before the MOT if the lamp is required.
Related MOT lighting guides
Frequently asked questions
Will one reverse light out fail MOT?
It can if that vehicle requires the reverse light to operate correctly.
What colour should reverse lights be?
Reverse lights should normally show white light.
Can reverse light stay on and fail?
Yes, if it operates incorrectly or causes confusion.
Is it usually just a bulb?
Often yes, but reverse switches and wiring can also fail.
Do LED reverse lights fail too?
Yes, LED units can fail or develop wiring faults.
Should I fix it before MOT?
Yes, lighting faults are usually worth fixing before the test.