Putting the wrong fuel in your car is an easy mistake to make, especially when you are tired, rushing to work or driving an unfamiliar vehicle. The important thing is what you do immediately after noticing the mistake.
Whether you have put petrol in a diesel car or diesel in a petrol car, do not start the engine if you have not already done so.
Starting the vehicle can circulate the incorrect fuel through the fuel system and potentially turn a simple fuel-drain problem into a more complicated repair.
What should you do after putting the wrong fuel in your car?
If you realise the mistake before starting the engine:
- Do not start the engine.
- Do not switch on the ignition unnecessarily.
- Move the vehicle to a safe location if possible without starting it.
- Inform the fuel station staff if you are still at the station.
- Contact a suitable roadside assistance or vehicle recovery service.
- Have the incorrect fuel removed before driving normally.
If you have already started the engine, switch it off as soon as it is safe to do so and arrange professional assistance.
Avoid trying to drive to a mechanic yourself.
What happens if you put petrol in a diesel car?
Putting petrol into a diesel vehicle can be particularly problematic because diesel fuel performs an important lubrication role in parts of the fuel system.
Petrol has different properties and can reduce the lubrication available to components designed for diesel fuel.
If the engine is started, the incorrect fuel can circulate through the fuel system and potentially affect components such as the fuel pump and injectors.
The severity depends on the vehicle, how much incorrect fuel was added and whether the engine was started.
What happens if you put diesel in a petrol car?
Diesel in a petrol vehicle can also cause problems.
Diesel does not ignite in a petrol engine in the same way petrol does. If the vehicle is started, it may run poorly, misfire, produce excessive smoke or stop running.
The fuel system may need to be drained and cleaned before the correct fuel is added.
Again, the safest response is to stop using the vehicle and arrange professional assistance.
What if you have only added a small amount of the wrong fuel?
Do not automatically assume that a small amount is harmless.
The effect depends on the vehicle, the amount of incorrect fuel and how much correct fuel was already in the tank.
Modern fuel systems can be sensitive, particularly diesel systems.
Rather than guessing whether the mixture is safe, have the situation assessed before driving.
What if you have already driven the car?
If you have driven the vehicle after putting in the wrong fuel, stop as soon as it is safe.
Do not continue driving simply because the car still seems to be running normally.
Once the incorrect fuel has circulated, the repair may involve more than simply draining the fuel tank.
A technician may need to inspect the fuel system and determine whether any components have been affected.
Can you fix wrong fuel yourself?
It is possible to drain fuel from some vehicles, but attempting to do it yourself can be unsafe if you do not have the correct equipment or knowledge.
Fuel is flammable, and modern vehicles can have complicated fuel systems.
There is also a risk of leaving contaminated fuel in the system or damaging components during an incorrect draining procedure.
For most drivers, professional fuel draining and recovery is the safer option.
How much can wrong fuel in a car cost to fix?
There is no single price because the cost depends on what happened after the mistake.
If the engine was never started and the contaminated fuel can be removed without further complications, the cost may be limited to fuel drainage and the correct replacement fuel.
If the vehicle was driven and components such as the fuel pump, injectors or other parts are affected, the repair can become considerably more expensive.
The vehicle’s make, model and fuel system also influence the cost.
Petrol in diesel vs diesel in petrol
The two mistakes are not identical.
Petrol in a diesel car can be particularly concerning because of the effect petrol can have on the lubrication requirements of some diesel fuel-system components.
Diesel in a petrol car can cause poor combustion and engine running problems because diesel is not designed to operate in a petrol engine in the same way.
In both cases, the safest response is to stop and get the incorrect fuel removed rather than continuing to drive.
Can wrong fuel damage the engine?
The incorrect fuel does not necessarily mean the engine is permanently damaged.
The outcome depends heavily on how quickly the mistake is identified and whether the vehicle was started or driven.
The longer the vehicle runs with the wrong fuel, the greater the possibility that contaminated fuel will circulate through the system.
That is why recognising the mistake early can make a major difference.
What if you notice the mistake while still at the fuel station?
This is one of the better situations because you may not have driven away yet.
Tell the station staff that the wrong fuel has been added.
Do not start the vehicle simply to move it away from the pump. If the vehicle needs to be moved, ask for appropriate assistance.
Arrange for the tank to be drained and refilled with the correct fuel before starting the engine.
How to avoid putting the wrong fuel in your car
A few simple habits can reduce the risk.
Before filling up:
- Check the fuel type recommended for your vehicle.
- Pay attention to the pump label.
- Avoid rushing while refuelling.
- Be extra careful when driving a rental or borrowed vehicle.
- If you drive both petrol and diesel vehicles, double-check before inserting the nozzle.
- Keep the fuel type clearly noted if several people use the vehicle.
Some drivers also keep a reminder near the fuel cap or dashboard, particularly when they regularly switch between different vehicles.
Wrong fuel during a long-distance journey
Putting the wrong fuel in your car becomes even more inconvenient when you are travelling between cities.
If the vehicle stops running far from home, you may need recovery assistance, alternative transportation and possibly accommodation depending on the situation.
For long journeys, it is useful to know who you can contact for roadside assistance and to avoid continuing to drive if you suspect a fuel mistake.
What if the car belongs to a business?
Wrong-fuel incidents can be especially disruptive for businesses that depend on cars, vans or other vehicles for deliveries and transportation.
A vehicle that is unexpectedly taken off the road can affect deliveries, appointments and customers.
Having a basic vehicle recovery plan can reduce the disruption while the affected vehicle is being inspected and repaired.
How Travo.ng can help when your vehicle cannot continue
A wrong-fuel incident can leave you stranded on the way to an airport, business meeting, delivery or interstate destination.
Travo.ng supports travel, transport and logistics needs, helping customers coordinate alternative transportation and journeys when their vehicle is unavailable.
If your vehicle needs to remain at a workshop after a wrong-fuel incident, arranging another way to reach your destination can help keep your plans moving.
The most important thing to remember about wrong fuel in a car is simple: don’t start the engine if you realise the mistake before starting it. If the engine has already been started, stop as soon as safely possible and arrange professional assistance. Acting quickly can help prevent a relatively simple fuel-drain problem from becoming a much more expensive repair.
