What Happens If You Put the Wrong Fuel in Your Car?
Putting the wrong fuel in your car is a surprisingly common mistake — and what you do next can make the difference between a simple fix and serious engine damage.
In this guide, we explain exactly what happens when the wrong fuel is added, what damage can occur, and what to do immediately to protect your vehicle.
Does the wrong fuel cause damage straight away?
Simply putting the wrong fuel into the tank does not always cause damage immediately.
The real risk begins when the engine is started.
If the engine has not been started:
In many cases, the fuel can be safely drained
The vehicle can often be fixed without long-term damage
If the engine has been started:
The wrong fuel can circulate through the fuel system
This can damage pumps, injectors, and the engine itself
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What happens if you start the engine?
Starting the engine allows the wrong fuel to be pulled from the tank and pushed through the fuel system.
This can lead to:
Contaminated fuel lines
Damaged fuel pumps
Injector failure
Engine misfiring or stalling
In severe cases, full engine failure
Modern engines are particularly sensitive, which is why starting the car is the most damaging step.
Petrol in a diesel car vs diesel in a petrol car
Petrol in a diesel car
Petrol acts as a solvent in diesel systems and removes vital lubrication.
This can:
Damage high-pressure fuel pumps
Cause injector failure
Lead to expensive repairs
Even a small amount of petrol in a diesel engine can cause issues if the car is started.
VS
Diesel in a petrol car
Diesel is thicker and harder to ignite.
This can cause:
The engine to fail to start
Excess smoke
Blocked fuel components
While often less damaging than petrol in a diesel car, it still requires professional attention.
What should you do immediately?
If you realise you’ve put the wrong fuel in your car:
Do not start the engine
Do not turn the ignition on
Do not attempt to drive the vehicle
Call a professional wrong fuel recovery service immediately
Acting quickly can prevent serious damage and save you thousands in repair costs.
Can a car recover from being misfuelled?
Yes — in many cases.
If dealt with early:
The wrong fuel can be drained
The system can be flushed
The correct fuel added
The vehicle returned to normal operation
The sooner the issue is handled, the better the outcome.
Is putting the wrong fuel in your car common?
Yes — misfuelling happens tens of thousands of times every year in the UK.
It often occurs:
When switching between vehicles
In hire cars
In work vans
At busy petrol stations
You’re not alone — and help is available.
When to call a wrong fuel specialist?
You should call for professional help if:
You’ve put the wrong fuel in the tank
You’re unsure whether the engine was started
The car won’t start after refuelling
A dashboard warning light appears
A specialist can advise you immediately and attend your location if needed.
Put the wrong fuel in your car? Don’t start it.
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