Which Bulbs Are MOT Tested?
| Bulb | Tested? | Failure If |
|---|---|---|
| Dipped beam headlights | Yes | Not working, wrong colour, incorrect aim |
| Main beam headlights | Yes | Not working, wrong colour |
| Sidelights (front position) | Yes | Not working |
| Front indicators | Yes | Not working, wrong colour, wrong flash rate |
| Rear indicators | Yes | Not working, wrong colour, wrong flash rate |
| Brake lights | Yes | Not working (all must work) |
| Rear tail lights | Yes | Not working |
| Rear fog light | Yes | Not working (at least one required) |
| Number plate light | Yes | Not working, wrong colour (must be white) |
| Reverse light | Yes | Not working |
| Hazard warning lights | Yes | Not working |
| Interior/boot lights | No | N/A |
Pre-MOT Bulb Check
Before your MOT, do a quick walkaround check:
- Turn on your lights and walk around the car.
- Check both indicators (front and rear) flash at the correct rate.
- Press the brake pedal (have someone watch or use a wall reflection).
- Select reverse gear and check the white reverse light.
- Turn on the rear fog light.
- Check both number plate lights are white and working.
Top tip: Buy a full replacement set of the most common bulbs (W5W, P21W, PY21W) and keep them in the glovebox. They cost under £10 and mean you can replace a blown bulb roadside.
Frequently Asked Questions
Can a blown bulb fail my MOT?
Yes — any external bulb that’s required by law (headlights, brake lights, indicators, etc.) will fail the MOT if it’s not working. It’s one of the most common MOT failure reasons.
Are LED bulbs an MOT failure?
Not automatically. Factory LED bulbs pass fine. E-marked retrofit LEDs should also pass. Non-approved retrofit LEDs may fail on beam pattern.
What happens if a bulb blows during the MOT test?
The tester will record it as a failure. You’ll need to replace the bulb and have the car retested (usually free if done within a set period at the same station).
