Car lights – what you need to know

Tips and advice about fog lights, headlights and more

Staying safe and avoiding fines – how to see and be seen

Driving in poor visibility can be at best unnerving and at worst hair-raising – whether it’s thick fog, double-speed-wiper driving rain, swirling mist or just stormy cloud. So here’s our guide to how and when to use different lights to help you see and be seen, and answers to some of the most frequently asked questions we hear about lights.

When should I use fog lights?

At the very least, you should use dipped headlights when visibility’s poor. You don't have to use fog lights, but it’s sensible to switch them on when visibility is really reduced so that other cars can at least see you. And your insurer might have an issue if you're involved in an accident in fog and they weren't switched on. Keep your eyes peeled for other drivers who aren’t using their lights. There are usually quite a few and it can be plain terrifying if another car suddenly appears at speed, seemingly out of nowhere, without their lights on. Rear fog lights are the most important, so other drivers can see you as they approach from behind. Front fog lights obviously help you to see the road ahead, lighting the road surface while minimising glare and reflection from the fog.

Remember to turn fog lights off once the fog clears. Rear fog lights used when visibility’s clear can obscure your brake lights and dazzle drivers behind. And you can be fined for misusing your lights.

What are dipped headlights?

Dipped headlights are your standard headlights for driving at night and in very poor visibility – i.e. those in between sidelights and main/full beam. European lighting regulations call these 'passing beam' because you drive on full/main beam unless you have to switch to passing beam to avoid dazzling another road user. If they're properly adjusted, dipped beams don't really light the road far enough ahead if you're driving much more than 40 mph.

Also known as low beam, dipped headlights give a better level of visibility the road, and allow other drivers better visibility of your car than is provided by side lights.

You can be issued with a £50 Fixed Penalty Notice if the aim of your dipped beam hasn't been correctly maintained and you dazzle other drivers

Should I use headlights during the day?

The Highway Code advice is for cars to use headlights whenever visibility's seriously reduced. Use of headlights during the day is recommended for motorbikes, to aid visibility.

What are the best lights for night time driving?

According to the Highway Code, you need to use sidelights between sunset and sunrise, and to use headlights at night except on a road with lit streetlights.

The safest option is to use dipped headlights at all times when driving at night, to see and be seen.

If you’re driving on dark country roads, main or full beam will help you see better but you must remember to switch back to dipped lights when you see a car coming in the opposite direction.

Dip your lights if you see any vehicles in front of you travelling in the same direction. If you leave your headlights on full beam, you’ll dazzle other drivers looking in their rear-view mirrors and wing mirrors. This isn't just for safety, etiquette and common sense – it's also a Highway Code regulation: ‘don’t use any lights in a way which would cause dazzle or discomfort to other road users’.

When should I use main beam lights?

If you're driving on unlit roads, main, high or full beam will help you see better but you must remember to switch back to dipped lights every time you see a car coming in the opposite direction.

Do avoid using full beam if you see any vehicles in front of you travelling in the same direction – you’ll dazzle other drivers looking in their rear-view mirrors and wing mirrors. As well as being a safety issue, it’s also a Highway Code regulation – ‘don’t use any lights in a way which would cause dazzle or discomfort to other road users’.

What's the law on flashing your headlights?

The Highway Code says you should only flash your headlights to let other road users know you're there – you're not supposed to flash your lights to convey any other message, or intimidate road users.

Some drivers flash oncoming cars to warn of hazards in the road, although you can be fined for doing this if you’re seen and considered to be ‘misusing your lights’. 

As the Highway Code states 'never assume that someone flashing headlights is a signal inviting you to proceed' (eg at a junction) – use your own judgement and proceed carefully.

If other drivers keep flashing you, there may be something visibly wrong with your car. You could have a broken bulb, you may have left your main beam or fog lights on by mistake, or you may have forgotten to switch your lights on. 

Remember, you can get a £50 Fixed Penalty Notice for lighting offences.

How and when should I use hazard lights?

The Highway code says you can use hazard warning lights when your car’s stationary, to warn that you're temporarily obstructing traffic – not as an excuse for illegal or dangerous parking. You shouldn't use hazard lights when being towed.

You can use hazard lights on a motorway (or unrestricted dual carriageway) to warn drivers behind you of a hazard or obstruction ahead. But remember to switch them off once your warning has been spotted. 

How often should I check my car light bulbs?

Don't be a one-eyed monster – cars with only one headlight are sadly a common sight on our roads. Check all your car lights at least once a fortnight, remembering number plate lights and fogs. Ask a friend to help, check reflections in a window, or check front and rear lights by driving/reversing up close to a wall. 

Can I be fined for having faulty car lights?

Yes – you can be issued a £50 Fixed Penalty Notice for 'lighting offences' such as a broken brake light. However, the police can give you a 'vehicle defect rectification notice' instead, if they wish. This means you have to get it repaired as soon as possible and provide proof (eg a mechanic receipt) to the police within 14 days.

Can my car fail the MOT if the car lights are faulty?

As part of the MOT test, lights are checked for: their condition, operation, headlamp aim, cleanliness, security and self-levelling. The tester also checks that the main-beam warning light on the dashboard is working. Products on the lens or light source that obviously reduce the light's intensity or change its colour are now a reason for failure. If HID (high-intensity discharge) lights or LED dipped beam headlamps are fitted, the tester will check the operation of any headlamp levelling and cleaning devices fitted. HID lamps can cause dazzle if they’re dirty or aimed too high.

Check your lights before taking the car for its MOT – replacement bulbs aren't expensive and some can be changed easily. Just check your car’s handbook. If the lights are hard to get to, or you’re not sure how to do it, a garage should be able to help.

Brake lights –  should I use the pedal or handbrake when stuck in traffic?

Sitting in a queue of traffic with your foot on the brake pedal dazzles the driver behind, so put your parking brake on.

How should I clean my car headlights?

Even if your lights are working fine, they'll need a regular clean. Winter grime builds up quickly but is easily removed in an emergency, or if you stop for a break, using screwed up newspaper or a rag. Give your number plate a wipe too. Car shampoo and water will probably do a better job of it, especially if there's a lot of stubborn dirt, bird poo or dead insects. 

If your car lights are clouding due to oxidisation, there are specialist products that can help.

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