When to Use Hazard Lights: UK Rules Explained

Summary

• Stationary only: Hazard lights are for when you're stopped and causing a temporary obstruction.
• Motorway exception: You can use them briefly while moving to warn of a hazard ahead.
• Not for illegal parking: Hazards don't make illegal parking legal.
• Don't use in rain or fog: They make it impossible to see your indicators.

Hazard lights are often misused. Some drivers use them as a "park anywhere" button. Others leave them on in heavy rain. Both are wrong.

This guide explains when you should and shouldn't use your hazard lights.

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What the Law Says

The Highway Code (Rule 116) states:

"You MUST NOT use hazard warning lights while driving or being towed unless you are on a motorway or unrestricted dual carriageway and you need to warn drivers behind you of a hazard or obstruction ahead."

In other words:

• Don't use them while moving (except on motorways/dual carriageways to warn of danger ahead)
• They're for stationary vehicles causing an obstruction

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When You SHOULD Use Hazard Lights

1. Broken Down

If your car has broken down and you're stopped in a dangerous position, turn on your hazards immediately. This warns other drivers you're not moving.

2. Temporary Obstruction

If you've had to stop suddenly due to an accident, obstruction, or emergency, hazards alert others to the problem.

3. Being Towed

If your car is being towed on a rope or A-frame (and doesn't have its engine running), use hazards to show you're being towed.

4. Motorway/Dual Carriageway Warning

If you're approaching slow or stationary traffic on a motorway, you can briefly flash your hazards to warn drivers behind. Turn them off once cars behind have slowed.

5. Stopped in an Emergency

If you've had to stop suddenly - perhaps a child ran out - hazards can warn others while you deal with the situation.

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When You Should NOT Use Hazard Lights

1. While Illegally Parked

Hazard lights don't give you permission to park on double yellow lines, in bus lanes, or anywhere else illegal. Traffic wardens will still ticket you.

2. While Driving in Rain or Fog

This is a common mistake. If you use hazards while driving:

• Other drivers can't see when you're indicating
• It can mask your brake lights
• It's confusing - are you stopped or moving?

Instead, use dipped headlights and, if visibility is below 100m, rear fog lights.

3. As a "Thank You"

Some drivers flash hazards to thank someone for letting them in. While not illegal, it can confuse other drivers. A hand wave is better.

4. To Pop Into a Shop

Stopping on a yellow line with hazards on doesn't make it legal. If you're loading, you may have some allowance, but a quick shop visit isn't loading.

5. While Moving on Regular Roads

Using hazards while driving on normal roads is illegal (except in the specific motorway situation above).

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Why Misuse Is Dangerous

Hazard lights have one purpose: to warn of danger. When people misuse them, they lose their meaning.

• Confusion: Is that car broken down, parking, or just being lazy?
• Hidden indicators: With hazards on, no one knows which way you're turning
• False sense of safety: Thinking hazards protect you while illegally parked is wrong
• Normalisation: When everyone misuses them, the real warnings get ignored

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Hazards vs Other Warning Lights

Situation	What to Use
Heavy rain while driving	Dipped headlights (not hazards)
Fog	Dipped headlights + fog lights if below 100m visibility
Broken down on motorway	Hazard lights (stationary)
Approaching slow traffic on motorway	Brief hazard flash, then off
Parked on unlit road at night	Sidelights (not hazards)

For more on lights, see our night driving guide and bad weather driving guide.

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Can You Be Fined for Misusing Hazards?

There's no specific fine for hazard light misuse. However:

• Using them while moving (except on motorways) could be "driving without due care"
• Using them while illegally parked won't prevent a parking ticket
• If misuse contributes to an accident, you could face prosecution

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Common Questions

Can I use hazards in a traffic jam on a motorway?

You can flash them briefly when you first encounter the jam to warn drivers behind. Once traffic behind has slowed, turn them off.

Should I use hazards when reversing?

No. Your reversing lights show you're reversing. Hazards would hide any indicators you might need.

Can I use hazards at a funeral procession?

It's not standard practice in the UK. Headlights on during the day is more common for funeral processions.

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Final Thoughts

Hazard lights have a specific purpose: warning others that your vehicle is a temporary obstruction or that danger lies ahead.

Using them for anything else - illegal parking, rain, or as a thank-you - dilutes their meaning and can cause confusion. Use them correctly, and help keep the roads safer for everyone.

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