Misfuelling & fleets: everything you need to know

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#Fleet Management
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Misfuelling your vehicle is an easy mistake to make and happens to around 150,000 UK motorists every year. However, misfuelling can be costly for your business as, depending on how much of the wrong fuel was put in, the engine may be damaged and in need of repair.

Drivers can save time and money by knowing what to do if they accidentally fill up their vehicle with the wrong fuel, so we’ve provided some top tips on how to resolve this mistake and detailed how you can prevent it from happening again.

What is misfuelling?

Misfuelling is simply when a driver puts the wrong type of fuel in their vehicle. Diesel vehicles are more prone to misfuelling as they have a wider fuel filler which can easily take a petrol pump nozzle, whereas the neck of the petrol filler is tighter than a diesel pump nozzle, making it harder to use the wrong fuel.

What is the potential damage of misfuelling?

Misfuelling can severely damage your vehicle and cost your business thousands of pounds. Misfuelling a diesel vehicle can be particularly detrimental, as diesel acts as a lubrication oil which helps to keep your vehicle running smoothly, however petrol acts as a solvent when mixed with diesel. This creates friction between parts and causes damage to the pump and fuel lines.  

It’s less likely for drivers to put the wrong fuel in a petrol vehicle but if this does happen there shouldn’t be any permanent damage. Petrol ignites by a spark from spark plugs, so if diesel is put into a petrol vehicle the spark plugs and fuel system will get blocked up and the vehicle will not start.

Drivers could also accidentally fill up their fuel tank with AdBlue which can lead to a costly repair bill. Turning on the ignition or starting the engine in this situation could cause expensive damage to your fuel tank, pump, and injection system. In addition, starting your engine with fuel in your AdBlue tank could be financially disastrous as you may need to replace the entire Selective Catalytic Reduction and AdBlue injection system.

What is the cost of misfuelling?

The cost of misfuelling can vary significantly depending on your situation. If you immediately realise your mistake at the pump, then a mechanic should be able to flush the fuel system out without causing internal damage to your vehicle.

However, the damage is more severe if the ignition has been started as this could result in an expensive repair of your vehicle’s fuel system or you could need a complete replacement of the fuel pump, diesel injectors, filters, and fuel tank.

How do you know if you’ve used the wrong fuel? 

It’ll be obvious if you’ve accidentally put diesel in a petrol vehicle as it will not start. However, if petrol has been used in a diesel vehicle there could be a few warning signs which are:

  • A loud knocking sound as you accelerate.
  • Excessive smoke from the exhaust.
  • Slow acceleration.
  • Engine warning light on.
  • The vehicle will not restart.

If you experience any of the above, then you should pull over when it is safe to do so and call a local garage or the AA who’ll be able to help you.

What should you do if you’ve used the wrong fuel in your vehicle?

Turning on the ignition after misfuelling causes the most damage to your vehicle, so it’s vital that you avoid doing this if possible. If you’ve realised you’ve used the wrong fuel before starting your engine you should:

  • Leave the engine switched off and avoid putting your key in the ignition.
  • Inform the staff at the petrol station what’s happened.
  • Put the car into neutral.
  • If requested by the petrol station staff, push the vehicle to a safe place.
  • Call your breakdown company or a local garage to drain and flush your fuel system.
  • Call your insurance provider as your policy may not cover misfuelling.
  • Report the incident to your fleet manager.

What should you do if you’ve started your engine after misfuelling?

If you’ve started your engine after filling up your vehicle with the wrong fuel, you should:

  • Pull over and turn off the engine as soon as it’s safe to do so.
  • Put the vehicle in neutral.
  • Call your breakdown company or a local garage to drain and flush your fuel system.
  • Call your insurance provider as your policy may not cover misfuelling.
  • Report the incident to your fleet manager.

How can you prevent misfuelling?

The best way to avoid misfuelling is to put a sticker on the filler cover to remind you what fuel is required. There are also handy anti-misfuelling devices you can implement in your fleet vehicles, such as a misfuelling prevention cap which only permits the exact diameter of a standard diesel pump nozzle, preventing drivers from accidentally using petrol.

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Karl Gurney
Head of Sales

Karl has over 14 years of experience in the fuel card industry and has a wealth of knowledge around the servicing and maintenance of fleet vehicles. Outside of work, Karl coaches a junior football team and enjoys spending time with his wife and 2 sons.