Filled your car with the wrong fuel? Here’s what to do next

Fuel economy

By James Mills 3 February 2014

Every four minutes a British driver puts the wrong fuel in their vehicle. Most fill a diesel car with petrol, as it’s nearly impossible to get the larger diesel nozzle into a petrol filler. If you’re one of the unlucky ones, follow these 10 steps to prevent serious damage to your vehicle.


  1. Do not start the engine

    This is the most important piece of advice. Assuming you have realised your mistake, do not start the engine. It will pump the wrong type of fuel through the engine’s vital components and could result in ruinously expensive repair bills.


  2. You can lock and unlock your car

    “It’s folklore that simply locking or unlocking your vehicle can prime the fuel pump, damaging it and the fuel lines,” says Brian Anderson, customer support and technical manager at Mercedes-Benz UK. So you can open the car, remove anything you need, and lock it again.


  3. Notify petrol station staff

    Staff at filling stations will have seen it all before and should be briefed on how to help misfuelling victims.


  4. Do not switch on the ignition

    “Turning on the ignition primes the fuel pump and, in some cases, initiates a sequence that starts the engine” says Chris Heekes, of Green Flag. “So when moving the vehicle, don’t switch on the ignition. Just disable the steering lock and have it pushed to a safe place on the forecourt.”


  5. Call for help

    This is not a problem that you can rectify at the roadside yourself. You will either have to call a breakdown organisation, or ring your garage and ask them to come and collect your car.


  6. Every detail counts

    Your garage should follow a formal procedure when it investigates the extent of the fuel contamination. “Mercedes-Benz dealers have a checklist to find out from the customer exactly what happened. We can then interrogate the car for further information, which can make a real difference if it was driven,” says Brian Anderson of Mercedes-Benz UK.


  7. Didn’t start the engine?

    “If the engine wasn’t started there’s a good chance no harm will have been done,” says Chris Heekes of Green Flag. “We’ll be able to remove the incorrect fuel from the vehicle’s tank, refill it with the right fuel and send you on your way without a bill or a worry.”


  8. If you did start the engine, don’t panic

    More often than not it’s possible for a garage to remove the incorrect fuel, flush the system with a cleaning agent and run the engine with the correct fuel.


  9. A vehicle’s warranty will be affected

    If a vehicle is under warranty then misfuelling it is likely to invalidate cover of the affected parts. Check with the dealer or vehicle manufacturer. It is also worth checking with your insurance company: some cover misfuelling.


  10. Don’t do it again!

    Distraction is the number one reason that drivers are hit by misfuelling misery. Concentrate at the pumps and consider fitting a device that makes it impossible to fill your vehicle with the wrong fuel. They only cost around £35 to £40.