Putting diesel in a petrol car is a common fuel mistake, but what you should do next depends on whether the engine has been started. The most important thing is to avoid driving the vehicle until the wrong fuel has been dealt with.
Diesel and petrol work differently, and putting the wrong fuel into your car can affect the fuel system and engine.
What Happens If You Put Diesel in a Petrol Car?
Diesel is heavier and less volatile than petrol. A petrol engine is designed to ignite petrol using spark plugs, while diesel engines use a different combustion process.
If diesel enters a petrol car, the engine may struggle to start, run poorly or stop shortly after starting.
Common symptoms can include:
- Difficulty starting the engine
- Misfiring or rough running
- Loss of power
- Excessive smoke
- Engine stalling
- Unusual noises
The severity of the problem depends on how much diesel was added and whether the vehicle was driven.
What If You Have Not Started the Car?
If you realise you have put diesel in your petrol car before starting the engine, do not start it.
Do not turn the ignition on unnecessarily either, because some vehicles can begin circulating fuel as soon as the ignition is switched on.
Instead, move the vehicle to a safe position if possible and arrange for the contaminated fuel to be removed by an appropriate professional.
This is usually the best-case situation because the wrong fuel may not yet have circulated through the fuel system.
What If You Already Drove the Car?
If you have started the engine or driven the vehicle after putting diesel in it, stop somewhere safe as soon as possible.
Do not continue driving simply because the car is still moving normally. Continuing to drive can circulate the wrong fuel further through the system and potentially increase the risk of damage.
Arrange for the fuel system to be drained and inspected before driving again.
Can Diesel Damage a Petrol Engine?
Diesel in a petrol car does not necessarily mean the engine is permanently damaged
