What happens if you refuel the car with wrong type of fuel?

Unfortunately, it often happens. If you accidentally refuel your car with the wrong type of fuel, but realize it in time, don’t switch on the ignition and don’t start the engine. This way you can prevent that the contaminated fuel get into the car system.

Case 1: Petrol in diesel car

Potential threats

The petrol in a diesel car acts as a solvent, reduces lubrication and can cause damage to the fuel pump. The metal particles in the damaged pumps can cause further problems in the fuel supply system.

What to do

  • Don’t switch on the ignition and don’t start the car.
  • Complete emptying of the tank is required: all contaminated gasoline must remove from the tank and replace by clean fuel charge. Only then you can start it.

Case 2: Diesel fuel in petrol car

Refuel the petrol car with diesel fuel is not really “easy” because the diameter of the diesel fuel filler gun is generally greater than the slot of petrol cars. But of course it occurs.

Signs that the petrol tank contains diesel fuel:

  • The engine starts only sometimes
  • The engine doesn’t start
  • The engine stops
  • While driving the exhaust strongly smokes

Potential threats

The petrol car works by using spark which is generated by spark plugs. If you refuel with diesel and you start the car, the diesel fuel can clog the candles and the fuel system, which can cause misfire, generate smoke and possibly the motor will stop too.

What to do

  • Don’t activate the ignition and don’t start the car
  • The car need a complete tank evacuation and then you have to fill it with clean fuel
  • Tip: If you refuel the petrol tank with diesel in any amount, use a special additive that removes residues of diesel from the fuel system.


It is also importan how much diesel fuel got into the petrol tank and how much spread it in the car’s internal system.

  • If less than 2 liters been included (in the tank it’s less than 5%)
    It is recommend to make a full tank draining, then filling the whole with petrol and thus it can’t cause any problems.
  • If more than 2 liters (more than 5% of the total tank)
    Don’t start the engine. Ask for help from an expert who removes and cleans the fuel tank. Once this happens, you can start and continue to use the car.
  • If you have already started your car
    If you started the car, it’s recommend to evacuate the fuel tank and flush the fuel lines, the entire system with clean petrol. Then fill up the car with petrol, and no further action is required.
  • You use of the car before realize the problem
    If you drive, while you detect it, stop as quickly as possible. The flushing of the lines and the flushing tank is essential in order to remove the contaminated fuel.

In each case it’s absolute necessary to replace the fuel filter.

In some vehicles may have problems due to the contamination of sensors and controllers. If you refuel the petrol car with diesel and have problems, consult with a professional.


How can you reduce the risk?

No one tank wrong fuel intentionally, but a lot of people make this mistake, even though, in the case of the two types of fuel, the filler size is different.

On each car is indicated what type of fuel use, usually in the tank cap and fuel filler cap as well. Always pay attention to these.

Always check twice the fuel type before you start to refuel!

The confusion rate can be higher if:

  • you use an unknown refuel station
  • you select brand by the color of the hoses
  • you use exchange car
  • you rent a car, which use a different fuel than yours
  • you buy a new car, which use different fuel than the old
  • you talk passengers during the refueling
  • you’re in late and hurry

Normally, after a contaminated fuel gets out of the car system, it will quite quickly become usable. But the more contaminated fuel is in the fuel system, the more expensive the repair can be. So always be careful when refueling!