Put the Wrong Fuel in Your Car? Follow These Steps

Put petrol in a diesel car or diesel in a petrol car? Learn the safest next steps and why starting the engine can make misfuelling more serious.

Petrol in a Diesel Car? What to Do After Putting in the Wrong Fuel

Realising that you have used the wrong fuel can be alarming, especially when you are already running late. The most important thing is to avoid starting the engine or switching on the ignition once you notice the mistake.

On some vehicles, opening a door or using certain controls can activate an electric fuel pump. Follow the advice of your breakdown provider or vehicle manufacturer rather than trying to move the car under its own power.

If you are still at the filling station

Leave the engine switched off and tell the forecourt staff what has happened. Ask for help moving the vehicle to a safe place if it is obstructing a pump, but do not attempt to drive it.

Contact your breakdown provider or a specialist wrong-fuel recovery service. Explain which fuel the vehicle requires, which fuel you added and whether the ignition or engine has been switched on.

Why petrol can damage a diesel fuel system

Diesel fuel provides lubrication to components within many diesel fuel systems. Petrol does not provide the same lubricating properties, and running a diesel engine on contaminated fuel can damage high-pressure fuel-system components.

The outcome depends on the vehicle, the amount of incorrect fuel and whether it has circulated through the system. Do not assume that adding more diesel will make the problem harmless.

What if diesel goes into a petrol car?

Diesel can interfere with combustion in a petrol engine, leading to poor running, smoke, misfiring or failure to start.

Even if the engine appears to run normally at first, stop using the vehicle and seek specialist advice. The correct remedy depends on the vehicle and the extent of contamination.

I have already driven away. What now?

Find a safe place to stop, switch off the engine and arrange assistance. Tell the recovery provider how far you drove and whether the car displayed any unusual symptoms.

Do not restart the engine to test whether the problem has disappeared. Further operation may circulate more contaminated fuel through the system.

How is a wrong-fuel incident repaired?

A specialist may need to remove contaminated fuel, inspect the system and carry out the cleaning or component replacement appropriate to the vehicle. If the engine has been run, additional checks may be necessary.

Ask for an explanation of the proposed work before authorising repairs. A fuel drain alone may not be sufficient in every case.

What if AdBlue went into the fuel tank?

Treat this as a separate contamination problem and do not start the vehicle. AdBlue is not a fuel additive and must not be mixed with diesel or petrol. Tell the recovery provider exactly what entered which tank.

How can I prevent it happening again?

Before filling up, check the fuel label inside the filler flap or in the vehicle handbook. Pay particular attention when using a hire car, a recently purchased vehicle or a car that someone else normally drives.

Need vehicle repair assistance?

Visit HON CAR SERVICE  to enquire about vehicle diagnostics and repairs. For an immediate wrong-fuel incident, contact a breakdown or specialist recovery provider first.