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Misfuelling cover: does car insurance include it?

You may think that putting the wrong fuel into a car is something that will never happen to you – yet misfuelling is easily done. It’s estimated that there are around 150,000 misfuelling incidents in the UK every year.

But how much damage can misfuelling do to your car, and is misfuelling cover included with your car insurance?

You may think that putting the wrong fuel into a car is something that will never happen to you – yet misfuelling is easily done. It’s estimated that there are around 150,000 misfuelling incidents in the UK every year.

But how much damage can misfuelling do to your car, and is misfuelling cover included with your car insurance?

Written by
Rory Reid
Car and technology expert
Last Updated
13 JULY 2023
5 min read
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What is misfuelling?

Misfuelling is when you put the wrong type of fuel into a vehicle.

In the vast majority of cases, it involves putting petrol into a diesel car. The nozzle on a diesel pump is much larger making it more difficult to misfuel a petrol car by mistake.

Unfortunately, putting petrol into a diesel car could potentially cause more serious damage to the engine than putting diesel in a petrol car, because it can increase friction and damage parts of the car.

Can I claim misfuelling costs on my car insurance?

Some insurance providers might cover misfuelling in the accidental damage part of the policy. Alternatively, you might be able to add misfuelling insurance to your current policy at an additional cost. Give your insurance provider a call to find out.

It’s important to check the terms and conditions to be sure you know what’s covered under misfuelling. Car insurance policies can vary greatly between providers. Some don’t provide any cover relating to misfuelling, while some might cover the costs of repairs. Some providers may cover the cost of draining and cleaning – and some both.

Make sure you know exactly what’s covered before committing.

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

  • If you realise your mistake at the pumps, don’t start your car.  
  • If you’ve already driven away, don’t panic. Find a safe place to pull over as soon as possible and turn off the ignition immediately.
  • Check your car insurance policy documents to see if misfuelling is covered. If it is, call your car insurance provider for assistance.  
  • If you have breakdown cover, call for assistance. Your cover may include the cost of towing, draining and cleaning.
  • If you don’t have breakdown cover, you can call a breakdown company to help out. However, they might need you to become a member or charge you an additional fee for the call-out.

How can putting petrol in a diesel car damage the engine?

If petrol runs through a diesel engine it can cause a significant amount of damage. This could end up costing thousands to repair and, in the worst cases, result in complete engine failure. 

Some of the main components that are affected by putting petrol in a diesel car are:

  • The fuel pump – diesel fuel lubricates the fuel pump as it passes through it. Running petrol through a diesel pump is a little like running an engine without oil. There’s a lot of friction and metal fragments can be ground off, which may then travel into the fuel system.
  • The fuel lines – if you drive off in your petrol-filled diesel car, the petrol will travel from the fuel tank along fuel lines towards the engine. The lines will need flushing or, worst case, replacing.
  • The filter – the fuel filter prevents contamination in your engine. If petrol has found its way to the filter, that will need replacing too. 
  • Fuel injectors – if metal fragments have been produced by the damaged fuel tank and they enter the fuel injectors, they can cause serious damage. The injectors have tiny holes, which, if blocked, would essentially ruin the system. This could result in a very hefty repair bill.

What happens if I put diesel in a petrol car?

Putting diesel in a petrol car is less serious than misfuelling the other way around, but it could still damage your vehicle. Petrol engines use spark plugs to ignite the fuel, but the lubricating diesel will block the spark plugs, leading to the engine not starting.

If you’re unlucky enough to have started the car without realising your mistake, you’ll find that the engine may start smoking. It might also cut out and stop.

What happens if I misfuel with E10 fuel?

If you put E10 in a non-compatible vehicle, your car will still run. A one-off mistake shouldn’t be too much of an issue — there’s usually no need to drain the tank. Simply fill up with the correct type of fuel as soon as you can. This will help dilute the E10 left in the system. However, if you continue to put E10 in your car, it could cause damage to its parts over time.

E10 petrol is considered a ‘cleaner’ type of fuel. It contains 10% renewable ethanol compared to premium unleaded, which contains just 5%. However, some older vehicles might not be compatible with E10 petrol. These can include classic cars and vehicles manufactured before 2011.

You can check whether your car is compatible with E10 petrol at GOV.UK.

Top tips to prevent misfuelling

  • Put a sticker on your car’s petrol cap to remind you which fuel to use.
  • Pay attention to the pump labels and always check it’s the right fuel before pressing the trigger.
  • Focus on filling up and don’t get distracted.
  • If you have a diesel car, you can buy a stopper that prevents narrow petrol nozzles from fitting in the neck of the tank.

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Frequently asked questions

Does breakdown cover include misfuelling?

Yes, unlike car insurance, most breakdown policies will cover on-site assistance, draining your car’s tank and recovery to a garage if needed. However, a breakdown policy won’t cover subsequent repairs if your car has been damaged because of misfuelling.

If you have breakdown cover, check the policy wording so you know exactly what’s covered.

What doesn’t misfuel insurance cover?

While misfuel cover can be a useful addition to your car insurance, policies can vary, so it’s important to read the small print.

Some policies may only cover the cost of repairs, not the cost of draining your tank. Others may cover both.

You might also find you’re not covered for:

  • Engine damage caused by misfuelling
  • Starting your car after misfuelling
  • Knowingly driving off after misfuelling.

Is it worth making a misfuelling claim on my car insurance?

Any claim you make on your car insurance, including one for misfuelling, is likely to push up the price of your next premium.

Before you put in a claim, you might want to weigh up the costs of recovery, repairs and any excess to see if it’s worth it.

Rory Reid - car and technology expert

Rory Reid is a car and technology expert. He serves as the main presenter on Auto Trader’s YouTube channel and was previously a host on BBC Top Gear and its sister show Extra Gear. He is also a presenter on Fifth Gear. Previously, he hosted Sky TV’s Gadget Geeks, CNET’s Car Tech channel, BBC Radio 5 Live’s Saturday Edition and on the YouTube channel Fast, Furious & Funny.

Learn more about Rory

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