IT is the soundest of advice but many motorists still do it.
Last year, there was a spate of thefts of cars in the Ormeau Road area of south Belfast during icy conditions.
Motorists switched on their engines to help defrost the windows only for thieves to jump into the cars and speed off.
Now the PSNI is reminding motorists that when defrosting frozen vehicles drivers should always remove keys from the ignition of the vehicle when they are not in the driver’s seat.
Police advise: “Never leave the vehicle with doors or windows opened or unlocked, even for the briefest of moments.
“Always take time to be aware of the immediate surroundings and persons moving around close by. Stay with your vehicle whilst defrosting it.
“All motorists should be aware that leaving the vehicle unattended with keys present may negate insurance cover against theft.”