Misfuelling a vehicle

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Misfuelling a vehicle is a common mistake to make, occurring on average every 3 minutes in the UK with roughly 150,000 motorists filling their tank with the wrong fuel every year.

Preventing misfuelling

If you’re used to driving several different vehicles, or fill up at many different petrol stations, here are a few tips to help avoid the cost and hassle of misfuelling.

  • Don’t rely on the colour of the hose or nozzle. Check the label on the pump trigger and the fuel grade indicator on the pump
  • If necessary, place a reminder inside or on the outside of the fuel filling flap
  • Keep your concentration at the fuel pump. It’s not a good time to get distracted
  • Try not to refuel when you’re in a hurry or stressed
  • If you drive a diesel vehicle and are worried about misfuelling, it is possible to purchase a device that fits into the filler neck to prevent you inserting the narrower petrol nozzle

What happens if you put petrol in a diesel vehicle?

Putting petrol in a diesel vehicle will damage the fuel pump if not dealt with immediately. In diesel cars, the main fuel pump uses the diesel fuel flowing through it for lubrication. However, when petrol fuel is put in, the mix of petrol in diesel acts as a solvent, reducing lubrication and quickly causing damage to the pump as the metal parts come into contact and rub together. Other parts of the fuel system which might not be compatible with petrol, can also be damaged.

Switching on the vehicle’s ignition will circulate this mix of petrol in diesel through the fuel system, causing further contamination to other components so if you realise what has happened straightaway, do not turn on the ignition.

What happens if you put diesel in a petrol vehicle?

Putting diesel in a petrol car is not especially common because the diesel nozzle is generally bigger than the petrol nozzle. The potential damage isn’t as severe but it will still cause the engine to smoke a bit and run badly, so it’s best to get the diesel out as soon as possible.

What to do next?

As mentioned above, the most important advice is to not turn on the ignition if misfuelling is suspected before driving off from the filling station.

Unfortunately, the removing of incorrect fuel is not something that can be carried out by the driver and it will need attention from either a roadside assistance company or removal to a garage or main dealer who will use specialist equipment to remove fuel from the tank. If the ignition has not been switched on, this may be all that is required. However, if the vehicle has been driven further work to flush the fuel lines may also be required and potentially replace any damaged components.

Due to strict Environment Agency rules relating to hazardous materials it is not possible to provide the driver with the contaminated fuel that has been removed from their vehicle.

If you are responsible for a vehicle fleet, all drivers should be made aware of what to do in the event of a misfuelling incident through the organisation’s driver manual. This information should also be available in each vehicle.


Under the QBE Motor policy, any claim for wrong fuelling of a vehicle will be considered under the accidental damage cover, provided always the insured has mitigated the loss which could mean, for example, not starting the engine or pulling over as soon as the error has been noticed. Each claim, however, would be looked at on its own circumstances. The cost of replacing the aborted fuel would however not be covered in any circumstances.


How can we help you?

For more advice on how we can help lower the cost of your risk, please email contact@rmpartners.co.uk


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