When stationary
You may use hazard warning lights to warn other road users that your vehicle is temporarily obstructing traffic—for example, after a breakdown or incident.
THE LIGHTS WARN ABOUT THE OBSTRUCTIONHighway Code Explained
Hazard Warning Lights: When Should You Use Them?
This hazard warning lights guide explains when they may be used while stationary, the limited exception while driving, and the common situations where switching them on is wrong or misleading.
✓ Highway Code Rule 116✓ Breakdowns and incidents✓ Created by a DVSA Approved Driving Instructor
Dashboard control
Both indicators flash togetherThey warn of a hazard—they do not give you permission to park.
The rule made simple
The Two Times Hazard Warning Lights May Be Used
Start by asking one question: is your vehicle stationary, or are you still moving?
When driving
You must not use them while moving or being towed unless you are on a motorway or unrestricted dual carriageway and need to warn drivers behind of a hazard or obstruction ahead.
USE THEM ONLY LONG ENOUGH FOR THE WARNING TO BE SEENThe crucial difference: stationary hazards warn people about your vehicle. Moving hazards briefly warn drivers behind about danger ahead. They are not a general “thank you”, “sorry” or “I will only be a minute” signal.
Interactive situation checker
Should You Switch the Hazards On?
Choose a situation to reveal the correct action and the reason behind it.
Use them
Broken down and causing an obstruction
Switch on your hazard warning lights to warn approaching traffic. If possible, move the vehicle off the road or to a place of relative safety.
Stationary vehicle temporarily obstructing traffic
See the distinction
Three Situations Learners Commonly Confuse
Broken down in the road
Your stationary vehicle is an obstruction. Warn traffic and get to a safer position if possible.
USE HAZARDSIllegal or dangerous parking
Hazards do not make the parking lawful or safe. Never use them as an excuse to stop where you should not.
DO NOT USE AS AN EXCUSEHazard ahead on a fast road
On a motorway or unrestricted dual carriageway, use them briefly to warn drivers behind, then switch them off.
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If your vehicle breaks down
Hazard Lights Are Only One Part of the Response
The lights warn other road users, but your first priority is reducing the danger to you, your passengers and approaching traffic.
Get off the road
If possible, move the vehicle to a place of relative safety rather than remaining in live traffic.
Warn traffic
Use hazard warning lights if the vehicle is causing an obstruction. Use sidelights in darkness or poor visibility.
Get people safe
Keep passengers away from moving traffic and do not stand where the vehicle could be pushed into you.
Get help
Contact recovery or the emergency services as appropriate and clearly communicate your location.
Warning-triangle trap: on an ordinary road, place a warning triangle at least 45 metres behind a broken-down vehicle if it is safe. Never place a warning triangle on a motorway.
Correct use versus misuse
What Hazard Warning Lights Do—and Do Not—Mean
They are for warning
A temporary stationary obstruction
A breakdown or incident affecting traffic
Danger ahead on a motorway or unrestricted dual carriageway
A brief warning that is switched off once observed
They are not permission
To park illegally or dangerously
To stop on double yellow lines “for a minute”
To drive slowly on an ordinary road
To replace normal indicators when changing direction
Quick knowledge check
Can You Avoid These Hazard-Light Traps?
1. When may you normally use hazard warning lights while your vehicle is stationary?
They may be used to warn that your stationary vehicle is temporarily obstructing traffic.
2. You are driving and meet a sudden queue on a motorway. What should you do with your hazard lights?
This is the moving exception: warn traffic behind, then switch them off once the warning has been observed.
3. Can hazard lights make illegal parking acceptable?
No. The Highway Code specifically says never to use them as an excuse for dangerous or illegal parking.
4. Where must you never place a warning triangle?
Never place or retrieve a warning triangle on a motorway because of the danger from high-speed traffic.
Common questions
Hazard Warning Lights FAQs
Can I use hazard lights while driving?
Only in the limited situation described by Rule 116: on a motorway or unrestricted dual carriageway, to warn drivers behind of a hazard or obstruction ahead. Use them only long enough for the warning to be observed.
Should I use hazards when I break down?
Yes, if your stationary vehicle is causing an obstruction. Move to a place of relative safety if possible and follow the appropriate breakdown procedure.
Can I park on double yellow lines with my hazards on?
No. Hazard warning lights do not make dangerous or illegal parking acceptable.
Can I use hazard lights to say thank you?
That is not their Highway Code purpose. They are a warning signal, and unnecessary use can confuse other road users.
How long should I use them to warn traffic behind?
Only long enough to ensure the warning has been observed. Leaving them on can hide your direction indicators and create confusion.
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