Definition
Fog lights are for low-visibility conditions: dense fog, heavy rain or heavy snow. Front fog lights are optional; rear fog lights — a more intense red than position lights — are mandatory and may only be used with visibility under 50 metres.
Key facts
- Rear fog lights are mandatory; front are optional.
- Using rear fogs in good visibility can dazzle other drivers and is fineable.
- Activate only when visibility falls below 50 m (dense fog, heavy rain, snow).
Practice real questions on this topic
Free DGT 2026 test with exam-style questions and explanations. No signup. Or explore the free DGT test in English hub for everything in one place.
In the DGT exam
- After being overtaken at night, your main beam may dazzle the driver now ahead. Which lighting must replace it?
- In which of these weather situations do the rules permit use of the front fog lights?
- Your vehicle is immobilised by an emergency inside a tunnel and a nearby SOS post is safely accessible. Through which facility should you request assistance without delay?
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