Misfuelling insurance – are you covered?

You may think that putting the wrong fuel into a car is something that will never happen to you. Yet misfuelling is surprisingly common and easily done. The AA estimates there are around 133,000 misfuelling incidents in the UK every year.

But how much damage can misfuelling do to your car, and is it covered by 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 surprisingly common and easily done. The AA estimates there are around 133,000 misfuelling incidents in the UK every year.

But how much damage can misfuelling do to your car, and is it covered by your car insurance?

Rory Reid
Car and technology expert
4
minute read
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Last Updated 7 SEPTEMBER 2022

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. This is because the nozzle on a diesel pump is much larger, so it’s more difficult to mis-fuel a petrol car by mistake.  

Unfortunately, putting petrol in a diesel car can also potentially cause more serious damage to the engine than putting diesel in a petrol car. Diesel is a more lubricating fuel, unlike petrol, which can increase the friction in your diesel engine parts. 

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, but 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, but they may need you to become a member or charge you an additional fee for 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, which 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. These 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, which can get very expensive. The injectors have tiny holes which if blocked, would essentially ruin the system. Now you’re looking at a hefty repair bill.

What happens if I put diesel in a petrol car? 

utting diesel in a petrol car is less serious than misfuelling the other way around, but it can still do damage to 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 may also cut out and stop. 

Can I claim misfuelling on my car insurance?

Some insurance providers may cover misfuelling in the accidental damage part of the policy. 

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. If they don’t offer misfuelling cover, you may want to shop around and find someone else who does.  

It’s important to check the terms and conditions to be sure you know what’s covered. Car insurance policies can vary greatly between providers. Some don’t provide any cover relating to misfuelling. Some will cover the costs of repairs, some the cost of draining and cleaning, and some both. Just make sure you know exactly what’s covered before committing to one. 

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