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Misfuelling cover

What is misfuelling insurance?

Rebecca Goodman
Written by  Rebecca Goodman
Beth Leslie
Reviewed by  Beth Leslie
5 min read
Updated: 09 May 2025

Key takeaways

  • Misfuelling insurance covers the costs if you accidentally put the wrong fuel in your car

  • If you realise you have used the wrong type of fuel at the pump do not start the engine

  • Petrol in a diesel car is more problematic and more expensive to fix

Refuelling a car

What is misfuelling?

Misfuelling is accidentally putting the wrong type of fuel in your vehicle.

It's surprisingly easy to do, especially if you're in a rush or distracted. The RAC calculate that in the UK about 130,000 people put the wrong fuel in their car each year.

Will car insurance cover misfuelling?

While some car insurance policies include misfuelling cover as standard, this is not common. You may be able to add it as an optional extra, but a lot of insurers will not offer misfuelling cover at all.

A misfuelling policy should cover the cost of draining and cleaning the fuel tank. It should also reimburse you for any fuel in your tank that was contaminated. It is likely to have restrictions, such as limits on how far you can drive with the wrong fuel in your tank.

What should I do if I put the wrong fuel in my car?

If you catch your mistake while still at the pump, the most crucial thing to remember is do not start your car. Doing so can cause significant damage to your engine. Instead, follow these steps:

  1. Remove the key from the ignition to ensure the engine doesn't engage.

  2. If possible, push your car to a safe spot or ask the station staff for assistance.

  3. Check your insurance documents to see if you have breakdown cover or misfuelling cover.

  4. If you're covered, get in touch with your insurer right away.

  5. If you're not covered, you'll need to call a breakdown service. This may come with a fee if you're not already a member.

If you've already driven away from the petrol station, find a safe place to pull over as soon as possible and turn the engine off. Put the car into neutral and move it somewhere safe if you can.

Then, call your insurer (if you have misfuelling cover) or a breakdown service.

What happens if you put the wrong fuel in your car?

This is the more problematic scenario. Diesel engines rely on the fuel's lubricating properties, which petrol lacks. If petrol is introduced to a diesel engine, it can cause friction and damage to components like fuel lines and pumps.

Symptoms of misfuelling a diesel car with petrol include unusual engine noises, smoke, reduced acceleration, and potential engine cut-outs.

Repairs for misfuelling when petrol is put into a diesel car are normally expensive and may require replacing the whole fuel system.

While not as severe, putting diesel in a petrol car can still lead to trouble.

Diesel can clog spark plugs and disrupt the fuel system. You might notice smoke and a struggling engine if this happens.

E10 fuel and misfuelling

E10 fuel was introduced in Great Britain in September 2021 and Northern Ireland in early 2023. It contains up to 10% ethanol, compared to the 5% in the previous standard E5. This change aims to reduce carbon dioxide emissions from petrol vehicles.

The government estimates that 95% of petrol-powered vehicles can run on E10 petrol. Most cars manufactured since 2011 should be compatible with E10, and many older vehicles are as well.

However, there are exceptions, including classic cars, certain makes and models, and mopeds. For these vehicles, 'super' grade petrol, which remains at E5, is recommended.

If you're unsure whether your car can handle E10, the government provides a tool that lets you check if your vehicle can use E10 fuel. Using E10 in an incompatible vehicle could lead to long-term damage, so it's worth checking before you fill up.

How do I find cheap misfuelling cover?

The best way to get a good deal on misfuelling cover is to compare different car insurance policies which include it.

MoneySuperMarket can make this work easier. Fill in your personal and vehicle information and specify that you want your policy to include misfuelling cover. We'll then show you a range of options to choose from.

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