Is it illegal to use front fog lights when it is not foggy?

Yes. The Road Vehicles Lighting Regulations 1989 permit front fog lamps only in conditions of seriously reduced visibility, and the Highway Code states as a MUST NOT that you may not use front or rear fog lights unless visibility is seriously reduced, and that you must switch them off when it improves. Seriously reduced visibility is generally taken to mean you cannot see for more than 100 metres. Police can issue a fixed penalty notice for misuse of fog lamps.

What is the point of front fog lights?

They produce a wide, flat beam with a sharp horizontal cut-off, mounted low on the car. In fog, light from a conventional headlamp reflects back off the water droplets and produces a wall of glare; a fog lamp sits under most of that and lights the road surface, the kerb and the white lines close to the car, which is what you actually steer by in fog. They are a supplement to dipped beam in bad conditions, not a replacement for it, and they are of no use whatsoever on a clear night.

Do front fog lights fail an MOT?

They do if the car was first used on or after 1 March 2018. Front fog lamps became a testable item in the May 2018 MOT changes, and on those vehicles a front fog lamp that does not work, has a lens defective enough to affect the light emitted, shows the wrong colour or is insecure is a major defect. On older cars front fog lamps are not inspected. Lamps that were never wired up and have no switch are not required to work at all.

Does my car have to have front fog lights?

No. Front fog lamps have never been mandatory on cars in the UK, which is why so many base models simply have blanking plates where the lamps would go. A rear fog lamp is a different matter: vehicles first used on or after 1 April 1980 must have one, fitted to the centre or offside of the car. So a car with no front fogs at all is perfectly legal and will pass its MOT; a car with no working rear fog will not.

Dashboard warning light

Front fog light warning light

Last updated 27 July 2026

Quick answer

The front fog lamps are on. Nothing is wrong, but like the rear fogs they may only legally be used when visibility is seriously reduced, and they must be switched off when it improves. The tell-tale is green, which distinguishes it from the amber rear fog symbol.

What to do: No action needed
Can you drive?: Yes

Why it is green

Confirms something is switched on and working. Not a fault.

What turns it on

Pressing or pulling the front fog switch, usually only possible once the sidelights or dipped beam are on. The inspection manual notes that fog lamps are allowed to operate independently of other lamps and the ignition, so the wiring varies quite a lot between makes.

What to do about it

Switch them off as soon as visibility improves. The legal restriction applies to front fogs exactly as it does to rear.
Use them with dipped beam, not instead of it. Front fogs throw a wide, low, flat beam that lights the road edge and kerb under the fog; they are not a substitute for a proper driving light.
Do not use them as styling lights on clear evenings. On many cars they are aimed low and wide enough to spill straight into oncoming drivers' eyes.
If the tell-tale lights but you cannot see the lamps working, get them checked before the MOT if the car was first used on or after 1 March 2018, when front fog lamps became a testable item.

Can you keep driving?

Yes

Yes, with the same caveat as the rear fogs. The car is fine; the restriction is on when you may use them. Front fogs dazzle less than rear fogs but they are still covered by the same rule, and using them in clear conditions is an offence.

What causes it

The front fog switch has been pressed, often accidentally when reaching for the headlamp switch
A single combined switch has turned on both the front and rear fog lamps together
The setting has carried over from a previous journey because the car does not reset it with the ignition

Does it fail an MOT?

Not on its own — but what causes it often does.

The front fog tell-tale is not a mandatory tell-tale and is not itself a defect. The lamps became testable with the 2018 changes, and under section 4.5 the tester inspects front fog lamps fitted to vehicles first used on or after 1 March 2018: an inoperative front fog lamp, a lens defective enough to affect the emitted light, the wrong colour or an insecure lamp are all major defects. Front fog lamps that are not wired up and have no corresponding switch are not required to work, and the tester gives the benefit of the doubt where it is unclear.

Common questions

Is it illegal to use front fog lights when it is not foggy?: Yes. The Road Vehicles Lighting Regulations 1989 permit front fog lamps only in conditions of seriously reduced visibility, and the Highway Code states as a MUST NOT that you may not use front or rear fog lights unless visibility is seriously reduced, and that you must switch them off when it improves. Seriously reduced visibility is generally taken to mean you cannot see for more than 100 metres. Police can issue a fixed penalty notice for misuse of fog lamps.
What is the point of front fog lights?: They produce a wide, flat beam with a sharp horizontal cut-off, mounted low on the car. In fog, light from a conventional headlamp reflects back off the water droplets and produces a wall of glare; a fog lamp sits under most of that and lights the road surface, the kerb and the white lines close to the car, which is what you actually steer by in fog. They are a supplement to dipped beam in bad conditions, not a replacement for it, and they are of no use whatsoever on a clear night.
Do front fog lights fail an MOT?: They do if the car was first used on or after 1 March 2018. Front fog lamps became a testable item in the May 2018 MOT changes, and on those vehicles a front fog lamp that does not work, has a lens defective enough to affect the light emitted, shows the wrong colour or is insecure is a major defect. On older cars front fog lamps are not inspected. Lamps that were never wired up and have no switch are not required to work at all.
Does my car have to have front fog lights?: No. Front fog lamps have never been mandatory on cars in the UK, which is why so many base models simply have blanking plates where the lamps would go. A rear fog lamp is a different matter: vehicles first used on or after 1 April 1980 must have one, fitted to the centre or offside of the car. So a car with no front fogs at all is perfectly legal and will pass its MOT; a car with no working rear fog will not.

This is general guidance, not a diagnosis. Manufacturers draw the same system differently and reuse symbols for more than one function, so check the handbook for your own car before acting on anything here.

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