It depends on the terms of your policy. Some policies cover roadside assistance and vehicle recovery but may not cover draining the tank, cleaning the system or repairing damaged components. Contact your insurer before authorising the work.
What Happens If You Put Petrol in a Diesel Car? Here Is What You Should Do
If you have accidentally put petrol in a diesel car, do not start the engine. Detecting the mistake before switching the vehicle on can make the difference between simply draining the tank and facing an expensive fuel-system repair.
If you have already started driving, stop in a safe place, switch off the engine and call roadside assistance. Continuing to drive may allow the incorrect fuel to reach the filter, high-pressure pump and injectors.
What happens if you put petrol in a diesel car?
Diesel fuel does more than power the engine. It also helps lubricate sensitive components within the injection system. Petrol has significantly lower lubricating properties, so it can increase friction and wear inside a diesel engine.
The risk is particularly high in modern common-rail diesel engines, which operate at extremely high pressures and use precisely manufactured components.
The parts most likely to be affected include:
- The fuel pump.
- The high-pressure injection pump.
- The fuel injectors.
- The diesel filter.
- The fuel lines and common rail.
The seriousness of the problem depends on how much petrol was added, how much diesel was already in the tank and, above all, whether the engine was started.
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What to do if you have not started the engine
Discovering the mistake before starting the car is the best possible scenario. The petrol will remain mainly inside the tank and should not yet have travelled through the injection system.
Follow these steps:
- Do not start the engine or switch on the ignition. In some vehicles, the fuel pump activates as soon as the ignition is turned on.
- Tell the petrol station staff.
- Do not start the car to move it away from the pump.
- Call roadside assistance and explain which fuel you added.
- Have the vehicle taken to a workshop so the tank can be professionally drained.
If the engine has not been started, the work will usually be limited to removing the contaminated fuel, cleaning the tank when necessary and refilling it with clean diesel.
What to do if you have already started driving
Once the engine has been started, the petrol may begin circulating through the fuel filter, pump and injectors. The car may initially appear to run normally because some diesel will still be present in the system.
If you are still at the petrol station, switch off the engine immediately. If you are already on the road:
- Reduce your speed without accelerating hard.
- Stop somewhere safe.
- Switch off the engine.
- Do not attempt to restart it.
- Call roadside assistance and request vehicle recovery.
Do not try to drive to the nearest workshop. Even a short journey can spread the incorrect fuel through more components and increase the cost of the repair.
| Situation | Risk level | Recommended action |
|---|---|---|
| The ignition has not been switched on | Generally low | Professionally drain and clean the tank |
| The ignition was switched on | Variable | Do not switch it on again and inform the workshop |
| The engine ran for a few seconds | Moderate | Switch it off and have the car recovered |
| The vehicle travelled several kilometres | High | Inspect and clean the complete fuel system |
Symptoms of petrol in a diesel engine
If the incorrect fuel reaches the engine, you may notice:
- Jerking or irregular engine operation.
- Loss of power.
- Poor acceleration.
- Unusual metallic or rough noises.
- Abnormal exhaust smoke.
- Warning lights on the dashboard.
- The engine suddenly stopping.
- Difficulty restarting the vehicle.
Do not wait for these symptoms to appear. If you know that you used the wrong pump, stop the vehicle even if it still seems to be running normally.
Can you dilute the petrol by adding more diesel?
Filling the rest of the tank with diesel is not a safe solution. Although this reduces the percentage of petrol, it does not guarantee that the mixture will provide enough lubrication for the pump and injectors.
You would also need to run the engine to use the contaminated fuel, allowing it to circulate throughout the complete injection system.
Do not add oil, additives or other substances either. The safest procedure is to remove the incorrect fuel and inspect the system if the engine has already been started.
How much petrol can a diesel engine tolerate?
There is no universally safe amount of petrol for a diesel engine. The consequences depend on the amount added, the diesel already in the tank, the age of the vehicle and the type of injection system.
Modern diesel engines are particularly sensitive because of the high pressures involved. Even if you have only added a small amount, you should not assume that it is safe to continue driving.
What will the workshop do?
If the engine has not been started, the workshop will normally drain the tank, remove any remaining contaminated fuel and refill it with clean diesel.
If the petrol has already circulated, additional work may include:
- Flushing the fuel lines.
- Replacing the fuel filter.
- Checking the high-pressure pump.
- Inspecting or cleaning the injectors.
- Looking for metal particles caused by internal wear.
The cost will depend largely on whether the engine was started and how long it continued running. Damage to the high-pressure pump or injectors can make the repair considerably more expensive.
What you should never do
- Do not start the engine to see whether the car still works.
- Do not drive to the workshop.
- Do not try to dilute the petrol.
- Do not add oil or fuel additives.
- Do not siphon the fuel out with a tube.
- Do not disconnect fuel lines yourself.
- Do not pour the contaminated fuel into a drain or onto the ground.
Petrol is highly flammable and should only be removed using suitable equipment. Attempting to drain the tank yourself can cause spills, fires and environmental damage.
How to avoid using the wrong fuel
Before refuelling, always check the label inside the fuel flap and read the name shown on the pump. Do not rely only on the colour of the nozzle, as colour coding may vary between petrol stations.
Take particular care when driving a rental car, a company vehicle or a model that uses a different fuel from your usual car.
At Lisbona Oil “El Visillo”, we have eight pumps offering microfiltered Premium Diesel, 95 petrol, 98 petrol and AdBlue®, with attended daytime opening hours and an automatic self-service option.
Drivers looking for a petrol station in Torre del Mar can check our location, opening hours and available fuels before visiting.
Microfiltered fuel and professional delivery services
In addition to choosing the correct fuel, its quality and cleanliness also matter. At Lisbona Oil, our fuels pass through special filters to provide customers with a microfiltered product.
Businesses, residential communities, agricultural operations and professionals can also use our diesel delivery service in Málaga.
Diesel vehicles fitted with selective catalytic reduction systems use AdBlue® in a separate tank. We also provide AdBlue delivery for companies and vehicle fleets.
Acting before starting the engine makes the difference
If you put petrol in a diesel car, remember the main rule: do not start the engine. Inform the petrol station staff, call roadside assistance and have the tank professionally drained.
If you have already started driving, stop safely, switch off the engine and do not restart it. The less time the engine runs, the lower the risk of serious damage to the injection system.
You can also read our latest article, Auto Plan 2030: When Does It Come Into Force and What Does It Mean for Your Car?, to learn more about vehicle purchase incentives and the future of combustion cars.
Frequently asked questions about putting petrol in a diesel car
Do not start the engine. Contact the rental company immediately and follow its instructions. The agreement may require you to use an approved recovery service or workshop, so you should not arrange repairs without authorisation.
Damage caused by using the wrong fuel may not be covered by the manufacturer’s warranty because it is not considered a manufacturing defect. Keep the workshop report, diagnosis and all related invoices.
Do not start the vehicle. Report the incident immediately and keep the receipt. Ask the station to record the time, pump number, type of fuel supplied and vehicle details. You should also retain workshop reports, quotations and invoices.
