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What To Do If You Put The Wrong Fuel In Your Car

What To Do If You Put The Wrong Fuel In Your Car



It can happen to anyone, and you aren’t the only person who will have misfuelled. The most important thing is the actions you take to rectify the mistake so you don’t cause further damage.

First and foremost DO NOT START THE ENGINE. We advise that you call a breakdown service immediately so they can drain the fuel out of your vehicle.

I have put the wrong fuel in my car, what do I do next?

The most important thing is that you don’t start your car, as this can cause damage that is expensive to repair.

Take your keys out of the ignition, and get someone to help you push the car somewhere safe.

What happens if you put diesel in a petrol car?

Filling your petrol car with diesel is less common, due to the nozzle on a diesel pump being slightly bigger (so won’t really fit).

If you do get diesel in your engine car, the main issue you will face is that your car won’t start. Petrol is flammable whereas diesel isn’t, and it ignites by a spark from your spark plugs. Diesel can block up your spark plugs and fuel system, meaning your car simply won’t start.

There shouldn’t be any permanent damage once the diesel has been drained out, but you will need to pay for your fuel tank to be flushed to get rid of the contamination.

What happens if you put petrol in a diesel car?

This is more common due to smaller petrol nozzles fitting easily in to diesel filter necks. What’s more, petrol can cause more damage to a diesel tank than diesel in a petrol engine does, so is a much more serious mistake to make.

Diesel acts as a lubricant in your car, helping the fuel pump do it’s job, whereas petrol acts in the opposite way and increases friction. The more petrol that goes through your diesel engine, the more damage it will do. This is why it is recommended that you don’t start your car.

This could damage your entire fuel system… and you may even need a new engine entirely! 

Do I still have to pay if I put the wrong fuel in my car?

Unfortunately, you will still have to pay for the incorrect fuel you will have filled up with. You will also lose what fuel was already in your car when this is flushed out.

However the cost of losing the fuel and flushing the system is much less than starting your car and causing more damage.

I have put E10 petrol in an incompatible car – what do I do?

You’ll have noticed the change from E5 to E10 petrol at pumps across the country from September 2021, but not all cars are E10 compatible.

Although putting E10 fuel in an incompatible car won’t do any short term damage, long term use could damage seals, plastic and metals, so we’d advise filling up with E5 as soon as you can, and mainly use this.

What do I do if I put fuel in my AdBlue tank?

Again, do not start your engine. This can be a very costly mistake if you do, as you might have to get your car’s Selective Catalytic Reduction (SCR) system and AdBlue System replaced.

As soon as you have realised your mistake, call a breakdown service immediately for help.

What do I do if I put AdBlue in my fuel tank?

Do not start the car, as the AdBlue can cause damage to your fuel tanks, pump and injection system. Call a breakdown service immediately, so they can tow you to a garage to have the AdBlue removed.

Advice for preventing mistakes when refuelling

  • Pay attention when filling up your vehicle - read the name of the fuel label at the pump, and don’t get distracted
  • Put reminders of the fuel your car runs on in your car e.g. on your keyring, or on the fuel cap
  • Buy a stopper for your diesel car’s filter neck, so the petrol nozzle doesn’t fit.