A clear, practical answer
How to Tell a Driver Their Lights Are On
Check the glass for a contact method — a QR code is the fastest, since scanning it sends an alert straight to the owner. Otherwise tell a nearby business or car park attendant. A note works but is only read when the driver returns, by which time the battery is flat.
CarQR · Last updated: 1 September 2026
Bu rehberi Türkçe okuWhy timing is the whole problem
Lights left on flatten most batteries within hours. A window left down ruins an interior in one shower. Both are entirely preventable if someone is told, and expensive if nobody is.
So the question is not only how to tell them, but how quickly.
Fastest: scan the QR code if there is one
If there is a QR sticker, point your camera at it. The page offers prepared alerts — "your lights are on" among them — and sending one puts a notification on the driver's phone immediately.
Neither your number nor theirs is shown, which is why telling a stranger costs you nothing to think about.
If there is a phone number
Call, or send a short message. Say what you can see, and add the registration and where the car is — it saves the driver a lot of guessing.
If the number is written openly, the driver is already paying for that. Just be the person calling in good faith.
If there is no way to make contact
In a managed car park or shopping centre, give an attendant the registration; most will announce it.
On a street, ask in the nearest shop — the car often belongs to someone working there.
In a residential block, tell the management.
A note is the last resort. It is read when the driver returns, usually too late for lights, still worth it for an open window.
For your own car
Picture the day this happens to you and nobody can reach you. A QR code on the glass is how you stay reachable without writing your number on it.
Step by step
- 1
Check the glass
Look for a QR code or a phone number.
- 2
Scan the code
Point your camera at it and send the prepared alert; it arrives at once.
- 3
Otherwise ask nearby
Give the registration to an attendant, security desk or nearby shop.
- 4
Leave a note last
A short note is read when the driver comes back.
Frequently asked questions
Should I knock on the window of a car with its lights on?
It may set off the alarm and disturb everyone nearby. Checking the glass for a contact method and asking an attendant works better.
What if a car door is open?
Do not get in and do not touch anything inside. Tell an attendant or a nearby business; in a busy place, telling the police is reasonable too.