The tester checks the one rear fog light every car first used from 1 April 1980 must have, and front fog lights on cars first used from 1 March 2018. Either fails if it's missing where required, not working, or likely to fall off. Front fog lights that aren't wired up and have no switch don't need to work.
Testers grade each defect: a major or dangerous defect fails the MOT, a minor one passes but is written on the certificate.
| Defect | Result |
|---|---|
| A front or rear fog lamp with a multiple light source up to 1/2 not functioning | PassesMinor |
| An obligatory rear fog lamp missing, or a front or rear fog lamp inoperative or in the case of a multiple light source more than 1/2 not functioning | FailsMajor |
| A lens defective which has no effect on emitted light | PassesMinor |
| A lens defective such that emitted light is adversely affected | FailsMajor |
| A front or rear fog lamp not securely attached | PassesMinor |
| A front or rear fog lamp likely to become detached | FailsMajor |
| Defect | Result |
|---|---|
| front or rear fog lamp switch inoperative or not operating in accordance with the requirements | FailsMajor |
| Defect | Result |
|---|---|
| Front or rear fog lamp emitted colour or position not in accordance with the requirements | FailsMajor |
| A rear fog lamp adversely affected by the operation of any other lamp | FailsMajor |
From DVSA's MOT inspection manual for cars and passenger vehicles. Contains public sector information licensed under the Open Government Licence v3.0.
In 2025, 158,829 car MOTs failed on fog lights: 0.50%, or about 1 in 200. Another 20,734 MOTs recorded it as a minor defect, which passes. Testers also noted it as an advisory on 505 MOTs: something to keep an eye on that didn't fail the test.
Share of the MOTs that failed on fog lights. One MOT can fail for more than one reason.
Share of car MOTs in each mileage band that failed on fog lights.
1.29% of MOTs on cars registered in 2005 failed on fog lights, against 0.17% for cars registered in 2022.
Models that failed on fog lights at least 1.15 times as often as the average car of the same age and mileage, out of 96 with at least 30 MOTs failed on it.
Least often: Mercedes E-Class (0.1×), Mercedes GLA (0.1×), BMW 5 Series (0.2×), BMW X1 (0.2×), BMW 1 Series (0.2×).
Yes, if a required one doesn't work
In 2025, 158,829 car MOTs failed on fog lights, about 1 in 200.
1 in 200car MOTs failed on fog lights in 2025
20,734minor defects recorded in 2025, which pass
The tester checks the one rear fog light every car first used from 1 April 1980 must have, and front fog lights on cars first used from 1 March 2018. Either fails if it's missing where required, not working, or likely to fall off. Front fog lights that aren't wired up and have no switch don't need to work.
In 2025, 158,829 car MOTs failed on fog lights: 0.50%, or about 1 in 200.
Against the average car of the same age and mileage, the Land Rover Discovery Sport (3.5 times as often), MG ZS (3.1 times as often) and Nissan Leaf (2.2 times as often), going by 2025 MOT results.