Headlights, fog lights and hazard lights: rules 113 to 116

Test yourself · 4

Four questions on lights and fog

Question 1 of 4

1. Fog has cleared and you can see clearly. What should you do with your fog lights?

   • A Leave them on to be seen
   • B Keep them on until you park
   • C Keep only the rear fog light on
   • D Switch them off Right

   The right answer is D: Switch them off

   WhyRule 236 says you must switch fog lights off when visibility improves.

   Source: The Highway Code, rule 236

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2. In fog, you can see only a short stretch of clear road ahead. The rear lights of another car are visible farther away. What should determine your speed?

   • A Matching the speed of the visible rear lights
   • B Maintaining the speed you used before the fog
   • C Keeping close enough to follow the other car's lights
   • D Stopping well within the distance you see clearly Right

   The right answer is D: Stopping well within the distance you see clearly

   WhyIn fog, you should be able to stop well within the distance you can see clearly; rear lights can mislead.

   Source: The Highway Code, rule 235

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3. You are driving in fog and a vehicle is following too closely behind you. Which of these should you **not** do?

   • A Check your mirrors before you slow down
   • B Use your brake lights to warn when slowing down
   • C Keep a safe distance from the vehicle in front
   • D Accelerate to get away from it Right

   The right answer is D: Accelerate to get away from it

   WhyIn fog, do not accelerate to get away from a vehicle that is too close behind (rule 235).

   Source: The Highway Code, rule 235

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4. In fog, why should you not trust the rear lights of the car in front to tell you your gap is safe?

   • A They can give a false sense of security Right
   • B They are always too bright
   • C They are not allowed in fog
   • D They hide the road signs

   The right answer is A: They can give a false sense of security

   WhyKeep a safe distance: rear lights can give a false sense of security. Be able to pull up well within the distance you can see clearly.

   Source: The Highway Code, rule 235

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The rule in plain words

Headlights (rule 113). Between sunset and sunrise your sidelights and rear number plate lights must be on. At night you must use headlights, except on roads with lit street lights (these usually have a 30 mph limit, or 20 mph in Wales). You must also use headlights whenever visibility is seriously reduced. For lights, night means from half an hour after sunset to half an hour before sunrise.

Dipped beam and dazzle (rules 114 and 115). You must not use your lights in a way that dazzles anyone, including people walking, cycling or riding horses. Use dipped headlights at night in built-up areas and on dull days so others can see you. If oncoming lights dazzle you, slow down and stop if you need to.

Fog lights (rules 114, 226 and 236). Seriously reduced visibility generally means you cannot see for more than 100 metres. Only then may you use front or rear fog lights, and you must switch them off when visibility improves. In the Highway Code’s words, fog lights “dazzle other road users and can obscure your brake lights”.

Hazard warning lights (rule 116). Use them when you are stopped and briefly blocking traffic. While moving, only on a motorway or an unrestricted dual carriageway, to warn drivers behind of a hazard ahead, and only long enough for them to see.

Which lights, when

What it means in practice

Driving in fog

Check your mirrors and slow down before you enter fog. Keep a safe gap: the rear lights of the car in front can give a false sense of security. Drive at a speed that lets you stop well within the distance you can see clearly (rules 234 and 235).

A car is too close behind you in fog

Do not speed up to get away from it. Check your mirrors before you slow down, then brake so your brake lights warn them (rule 235).

The fog lifts

Switch your fog lights off straight away. Left on, they dazzle drivers behind and can hide your brake lights (rule 236).

Common mistakes

• Leaving fog lights on after the fog has gone. You must switch them off.
• Using fog lights in rain or at night when you can see well. Only when visibility is seriously reduced.
• Main beam towards oncoming traffic. Dip your lights so you do not dazzle.
• Hazard lights to park somewhere you should not. They are never an excuse for dangerous or illegal parking.
• Hazard lights while driving on an ordinary road. Only on a motorway or unrestricted dual carriageway, briefly, to warn of a hazard ahead.

Questions about car lights

When should you use fog lights in the UK?

Only when visibility is seriously reduced, generally when you cannot see for more than 100 metres. Switch them off as soon as visibility improves. Source: rules 226 and 236.

When must you use headlights?

At night, except on roads with lit street lights, and whenever visibility is seriously reduced. Source: rule 113.

Can you use hazard lights while driving?

Only on a motorway or unrestricted dual carriageway, to warn drivers behind of a hazard or obstruction ahead, and only long enough for them to see it. Source: rule 116.

What should you do if oncoming headlights dazzle you?

Slow down, and stop if necessary. Source: rule 115.

Read next

• Driving in bad weather quiz
• Safety and your vehicle theory test questions
• Stopping distances in the Highway Code
• More Highway Code rules, explained

Sources

(2)

1. The Highway Code, rules 113 to 116 (lighting requirements), GOV.UK. Checked 4 November 2026.
2. The Highway Code: driving in adverse weather (rules 226 to 237), GOV.UK. Checked 4 November 2026.

Contains public sector information licensed under the Open Government Licence v3.0. Quotes from The Highway Code are Crown copyright. Sources and image credits.