1. Home
  2. Car insurance
  3. Car insurance guides
  4. Engine idling law: is idling illegal in the UK?

Engine idling law: is idling illegal in the UK?

Idling car engines are annoying and unhealthy - pumping out exhaust fumes while you're walking along the pavement or sitting outside a cafe. But drivers who don't cut their engines when waiting aren't just wasting fuel and damaging the environment. They're breaking the law and risk being fined.

A car with fumes while stationary

Idling is when a stationary car is left with its engine running. The car isn't moving, and all the while it churns out noxious emissions.

These emissions kill about 4,000 people each year, the Guardian reports. To try and reduce this, councils have been targeting drivers who idle.

There are some times when you can't avoid idling, for example when you’re in traffic or stuck in a queue. But you should always switch your engine off if you can. This includes being in gridlocked traffic, stopping outside school or picking up a passenger.

You might also think there’s no harm leaving your car idling in your drive. However, this could also have an impact on your car insurance, as you’re making your vehicle susceptible to thieves if you leave it unattended.

Compare car insurance quotes

Idling engines cause significant air pollution.

An idling engine can produce up to twice the emissions of a car in motion. It pumps out unnecessary sulphur dioxide, particulate matter and nitrogen oxide into the atmosphere.

These chemicals all have a negative effect on air quality and contribute to asthma, heart disease and lung cancer.

Research has found that an idling car causes enough emissions to fill 150 balloons with harmful pollutants every minute.

It’s a common misconception that turning your engine off and on again uses more fuel than leaving your car idling. Unless your car has ‘stop-start’ technology you should switch your engine off, so long as it’s safe to do so.

But if you drive an older car, it’s wise to plan ahead rather than turning your engine on and off.

Doing so could affect the battery, especially if it’s more than 5 years old.

Stationary idling is an offence under Section 42 of the Road Traffic Act 1988.

The act enforces Rule 123 of the Highway Code, that states:

“You must not leave a vehicle’s engine running unnecessarily while that vehicle is stationary on a public road. ”

If you’re caught idling you could be hit with a £20 fixed-penalty fine under the Road Traffic (Vehicle Emissions) Regulations 2002, rising to £40 if unpaid within the required timeframe.

Fines can be as high as £80 in certain areas of London where there are additional measures to cut emissions.

An article by the Guardian in 2022 revealed more than 70,000 idling drivers were reported through the council's "report it" toolsince 2017 in Westminster.

Only 63 fines of £80 were issued though, and only half of these were paid.

In 2021, Nickie Aiken, the MP for Westminster asked the government to increase the £80 fine. She stated that £80 isn't an effective deterrent for people to turn of their engines.

Aiken says:

“Tackling air quality is a major priority for my constituents – and therefore me,”

"From my experience, when I introduced the ‘don’t be idle’ campaign as council leader, the vast majority of drivers who are asked to turn off their engines do so. Perhaps that is why we have very few fines given out. For those who refuse, £80 doesn’t seem to cease their behaviour. Perhaps a larger fine will focus their minds.”

Wales has also introduced a fixed penalty notice for idling. According to Torfean Council, a fine is only issued if the driver refuses to turn off their engine if they're told to do so by an authorised officer.

The council also said it wouldn't penalise drivers if they were idling their engine to de-ice their windscreen or cool their vehicle on a hot day.

What else has the government done to cut emissions?

Along with the laws on idling, the government has also introduced other measures in an effort to improve the air quality in the UK. This includes cutting speed limits on motorways.

Cities across the UK are also launching Low Emission Zones that fine drivers with high-polluting vehicles. This is part of the Clean Air Bill.

A higher tax on diesel cars was introduced in an attempt to reduce nitrogen oxide, and in 2030 the government will ban the sales of new petrol and diesel cars.

Speed bumps might also contribute to emissions, so governments and local councils are considering new forms of traffic calming measures.

No. More manufacturers are building new cars with stop-start technology. This means that the engine stops when the car does, and only comes back on when you next apply the clutch.

The car uses a computer to detect when the car has come to a standstill, stopping fuel delivery and spark to the engine.

This technology saves drivers fuel, reduces emissions and could stop you from getting a fine for idling.

The rules over vehicle idling apply to public roads only, so you aren’t breaking the law if you idle in your drive, or in a supermarket car park, for example.

However, just because it’s not illegal doesn’t mean it’s the right thing to do. You’re still chucking just as many toxic fumes into the air regardless of whose land you’re on.

You shouldn't leave your car idling even if you're waiting for someone - it's illegal if you're on a public road. If you’re waiting for someone, it’s best to switch the engine off. You should also turn your engine off while:

  • Loading and unloading your vehicle
  • Waiting at car parks and lay-bys
  • Parking in set-down and pick-up points

On the rare occasion where you might be in a heatwave, keeping the air-conditioning on can seem like a sensible reason for idling.

Usually you can keep the air conditioning running by leaving the ignition on but not the engine.

If there’s no choice but to leave the motor running you should try to keep waiting down to a minimum.

You can leave your engine on to de-ice your windscreen but it should only be for a few minutes and you shouldn't leave your vehicle while the engine is running. If you get out to scrape your windscreen or leave your vehicle entirely, you could be penalised for not being in control of your vehicle while the engine is running.

There are a couple of ways you can de-ice your windscreen and avoid this. You could scrape the ice off with an ice scraper and de-icer or another home made solution if you need it. Once you've done this you can sit in your car and turn on your heating to melt away any stubborn icy areas.

Or you can sit in your car with the heat on to loosen the ice. Once it's defrosted a bit, turn off the engine and then de-ice your windscreen with your usual tools.

Whatever you do, never leave your car unattended when your engine is idle, even if you're leaving it to de-ice your windscreen or letting your blower get rid of condensation. It's a perfect opportunity for thieves to steal your car, resulting in a car insurance claim.

Vehicle idling isn’t just bad for the environment, it can be bad for your car too. This is because when your engine is running but your car is stationary, the engine isn't operating as efficiently as it should. The fuel may not combust properly, leaving behind a residue that could, in time, harm your exhaust.