Is it illegal to leave your engine running while you defrost your vehicle?

Is it illegal to leave your engine running while you defrost your vehicle?

15 December 2020 | A Merrick | 6 min read

Can you leave your engine on to defrost the windscreen?

You aren't the first person to have done it, and you won't be the last. Many leave the engine running to defrost their car or van. Vehicles are often covered with heavy frost or ice when the temperature drops in the UK - an all too familiar scene every winter. So when you come out on a freezing morning, first things first, you turn the engine on and fire up the heater. Then, you pop back inside and wait for your car or van to defrost. But is this legal?

Very few realise that leaving your vehicle running on a public road while unattended is illegal. It is an offence that violates Rule 123 of the Highway Code:

You MUST NOT leave a parked vehicle unattended with the engine running or leave a vehicle engine running unnecessarily while that vehicle is stationary on a public road.

The emphasis on the above road law is on 'public road.' If you leave the vehicle untended while running on a private driveway, then the above won't apply. So, if you are on a public road, find alternative ways to de-ice a van or remove the frost from your car and avoid fines this winter.

There are many other reasons why you shouldn't leave a vehicle unattended with the engine on. Vehicle theft is still a problem, with over 113,000 cases of motor vehicle theft in the UK in 2019/2020, with 'Frosting' being the given term for vehicle theft in the winter. Imagine if the keys are in the ignition already, the engine is running, the vehicle is nice and warm, and there's no one else around... it's an ideal Christmas gift for a thief. Not to mention that insurance policies become invalid if you have left the car unattended with the keys in it. Resulting in an expensive payout to replace the vehicle and its contents if it's stolen. So don't leave yourself vulnerable to thieves this season.

car theft in the winter

How should you de-ice the windscreen?

It is also worth noting that you have to defrost the vehicle somehow, or you could end up with a fine for driving with an obscured view. You must clear the whole windscreen (not just the driver's view) to drive your car or van safely. Don't forget you must clear windows, mirrors and lights too. So, if you can't leave the vehicle on its own while you wait for the engine to de-ice it, what can you do?

  • First, turn on the engine, but stay with the vehicle. If you need to head back inside, switch off the engine and securely lock the car.
  • Second, let the heated air circulate. This is to absorb additional moisture in the vehicle.
  • Next, brush off snow or light frost and use a scraper to remove ice. Gently lift your wipers to protect them when scraping. Use a de-icer solution to assist in the process.
  • Then, only once the windows, mirrors, and lights are clear, you're ready to go.

We advise that you do not use hot water to de-ice your car or van. How many times have you seen someone running outside with a kettle and pouring it over the windscreen? This is not only dangerous for the driver but is a risky technique that cracks and breaks the glass, so it could end up leaving you in hot water!

Modern remote heating technology

Further to the above, some manufacturers offer remote heating on new vehicles- an advantageous development in motor vehicle technology. FordVolvo, and Land Rover have new models with remote heating, meaning a driver can warm the car without having to wait with it. Better yet, many electric and plug-in hybrid vehicles are fitted with a 'pre-heat tool that will warm the car or van while it is plugged in. An excellent option for those considering an electric van this year or an electric car. Many of our customers are switching to electric and hybrid, especially since the UK recently announced the ban on the sale of petrol and diesel cars by 2030.

Don't get caught out by leaving the engine running to defrost your car while you finish your morning coffee indoors. Remember, this applies to vehicles on a public road. Follow our advice on de-icing it safely to avoid theft, accidents and fines this winter.

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