Knowledge Base Categories

Wed, 14/06/2017

There is a great deal of conflicting information about the benefits and drawbacks of engine idling. Here are the main effects of engine idling:

  • Engine idling wastes fuel (and therefore money)
  • Engine idling leaves fuel residue, damaging engine components such as piston rings, cylinders and spark plugs (which in turn can increase fuel consumption by up to 5%)
  • Engine idling contributes to air pollution
  • In certain locations in London, you may be fined for idling your engine

Some common myths about engine idling, debunked:

  • Myth: Turning the engine off and on causes more pollution Starting an engine only causes more pollution than idling if you turn it off and restart it within a minute. If you would have idled for longer, you would have wasted more fuel.
  • Myth: You need to keep the engine running to charge the battery With modern batteries you do not need to keep the engine running to keep the battery charged.
  • Myth: Turning the ignition causes wear and tear With modern ignitions, turning the car on and off creates less wear and tear than idling.

Can you be fined for idling your engine?

Do you leave your engine running while you’re parked up, for example if you are waiting to pick up a passenger? If you do this, particularly in central London or outside school gates, you now run the risk of facing a fine.

In February 2017, Westminster council enforced new rules which mean drivers could face an £80 fine for leaving the engine idling for more than a minute while parked. Cars, vans, coaches and taxis could all be penalised, though offenders will usually receive three written warnings before being given the penalty.

Meanwhile, three schools in London are handing out £20 fines to parents who don’t switch off their engines while dropping off or picking up their children. This is all in a bid to reduce air pollution, particularly in London where pollution is a particular problem, and around schools to try to keep children safe and healthy.

What are the rules about engine idling?

Engine idling means running your engine when it is not necessary for the examination or operation of your vehicle. This means that it’s fine to run your engine if you have broken down and are fault-finding, and there’s also no need to switch off the engine if you are waiting at traffic lights, for example. However, some car manufacturers offer “stop-start” technology, which cuts the engine while the vehicle is stationary, for example if you are waiting in traffic, and restarts it when you release the brake pedal.

If you’re parked for more than a minute, there is no need to keep your engine running and this is an offence.

Fines for leaving an engine running are nothing new. Stationary idling is an offence under section 42 of the Road Traffic Act 1988, and in 2002 local authorities were given the power to hand out fines. The act enforces rule 123 of the Highway Code, which states: “You must not leave a vehicle engine running unnecessarily while that vehicle is stationary on a public road.” Breaking this rule can incur a £20 fine, which increases to £40 if left unpaid for a certain amount of time.

How does engine idling affect the environment?

Engine idling is an avoidable contributor to both air and noise pollution. For every litre of fuel used by a diesel engine, 2.64 kg of CO2 is released. Stopping unnecessary idling can help to improve the air quality, and in turn improve the respiratory and cardiovascular health of everyone within our community. Contrary to popular belief, with modern vehicles, it is cheaper and less harmful to the environment if you turn off the engine and start it again a minute or more later, rather than leaving the engine running.

What are the negative effects on your vehicle?

Idling your engine is a waste of both fuel and money, and with fuel making up at least a third of the average driver’s running costs, it’s in every motorist’s best interest to kick the habit.

But engine idling doesn’t just affect the environment and your wallet, as a factsheet from FORS explains. An idling engine can leave fuel residue that can cause oil contamination and damage engine components such as cylinders and piston rings. Engine idling can also make your spark plugs become dirtier more quickly, which in turn can increase your fuel consumption by 4-5%. Water will also condense in the car’s exhaust system, which can lead to corrosion.

Leaving your engine running for a minute or two while you wait for a passenger to get in might not sound like a big deal. But if you do this on a regular basis, every minute adds up, using up fuel and costing you money you otherwise could have saved. With 9.9 million drivers in London alone, if everyone made small changes to their driving habits, we could significantly reduce the pollution caused by our vehicles.