Have you put the wrong fuel in your car? Our step-by-step guide will take you through exactly what to do and what misfuelling symptoms you should look for.
Putting the wrong fuel in your car could damage the engine and be expensive. Yet, misfuelling is an unfortunate slip-up that the RAC says 150,000 of us do each year.[1]
Follow our step-by-step instructions to learn what to do, the symptoms to look for, and the cost implications.
EASY AS HACK
If you put the wrong fuel in your car, do not start the ignition.[2] Even if you just push or turn the key to the lights-on-dash stage, it could cause the fuel pump to kick in and draw in the incorrect fuel.[3]
At a glance
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Checklist - If you’ve used the wrong fuel: |
What to do if you’ve put the wrong fuel in your car
Don’t panic if you put the wrong fuel in your car. It’s a common mistake but can be fixed if you act fast and don’t turn on the engine.
Accidentally pumping incorrect fuel in your car is easily done when you’re distracted or tired and on autopilot.
You can minimise potential damage if you realise what you’ve done straight away. First, don’t panic. Second, and most importantly, do not start the ignition.[4]
Even if you just push or turn the key to the lights-on-dash stage, it could cause the fuel pump to kick in and draw in the incorrect fuel.[5]
Symptoms of putting the wrong fuel in your car
If you put the incorrect fuel in your car and turn the ignition, these are the symptoms you might experience:
- The engine misfiring
- Loss of power
- Failing to restart
- Unusual smells and noises
- Loud knocks when accelerating
- Your exhaust gives off smoke
The misfuelling symptoms will vary depending on which fuel you use.1 Loud knocking sounds and slower acceleration are likely if you put petrol in a diesel car.[5]
At any rate, it will quickly become apparent that something is critically wrong with your vehicle.
Steps to follow when you’ve put the wrong fuel in your car
1. Keep your engine off
- Don’t try to start your car, as it can cause permanent damage once the fuel begins moving through the engine. The result could be expensive repairs.
- It’s safest to remove the keys from the ignition to avoid any chance of the fuel pump kicking in.
2. Put your vehicle in neutral
- Your vehicle must be in neutral so you can move your car (with help from a passenger, another driver or a garage attendant) to a safe place.
- Leaving the car in gear could prime the pump to begin circulating the fuel as you push the vehicle.
- If automatic, you may need to take the handbrake off as it might have automatic handbrake on and you have to take it off when its in neutral?
3. Alert petrol station staff
- If you’re lucky enough to have noticed you have put the wrong fuel in your car before driving off, notify staff at the petrol station immediately.
- They can help you push your car to a safe spot on the forecourt.[5]
4. Get to a safe place
- Whether you are still at the petrol station, have driven off the forecourt, or are on the road, you should push your car to a safe location.
5. Call your breakdown provider immediately
- Call your breakdown provider once you have pushed your vehicle to a safe place.
- Your breakdown specialist will drain the wrong fuel from your car’s system and make it safe to refuel again.
- Get in touch with your insurance provider to see if they cover misfuelling.
If you worry about accidentally putting the wrong type or grade of fuel into your car’s fuel tank, Ageas Car Insurance includes wrong fuel cover as standard. We’ll pay to drain and flush your fuel tank and any damage to your engine directly caused by accidentally putting the wrong fuel in your car. We don’t cover replacement fuel.
What to do if you have already started your engine after misfuelling
1. If you have started your engine after misfuelling and realise your mistake instantly, stop your car as soon as it is safe.[1]
2. If you are still in the petrol station, turn your engine off, put the car in neutral, take off the handbrake and get help pushing your vehicle to a safe place.[2]
3. Call your breakdown provider and explain that you put the incorrect fuel in your car.[1]
What happens if you put petrol in your diesel car?
Pumping petrol into your diesel car or van is more likely because a petrol nozzle is small enough to fit into the fuel entry point. In contrast, a diesel nozzle is bigger than most petrol fillers.[2]
Introducing petrol into a diesel car is a more severe problem than vice versa, especially if you start the engine. The two fuels ignite engines differently – spark plugs ignite petrol, whereas compression ignites diesel. The engine will not correctly function if you mix fuels.
Filling a diesel car or van with petrol can be disastrous because petrol increases friction, reducing the lubricating effects of diesel on moving parts like the fuel pump, causing havoc with the fuel system and engine.[7]
Putting petrol in a diesel car and starting the engine can cause irreversible and expensive damage.[7] The engine will misfire, affecting the car’s power, acceleration, and performance. You might need new fuel pumps and injectors or even an entire engine.
What happens if you put diesel in your petrol car?
Filling a petrol car with diesel by mistake is difficult because you’d have trouble fitting the nozzle into the fuel filler. But if you manage to put diesel fuel in your petrol tank, it’s vital not to start your engine.
If the diesel gets into the fuel system, it could block it because diesel is thicker than petrol. If it coats the spark plugs, the petrol won’t ignite correctly, will misfire, and fail to start. Diesel fuel could also harm the fuel pump, injectors and fuel lines.[7]
However, by acting fast and getting someone to drain the fuel, you should not cause any permanent damage.[7]
How to avoid misfuelling your car
The most likely reason for putting the wrong fuel in your vehicle (misfuelling) is that your attention was momentarily elsewhere.
So, the first step in avoiding misfuelling your car is to focus on the vehicle and the pump.
The next step is to double check the signage around the petrol station, especially if it’s one you haven’t visited before. Then, you’ll notice that the hose colour and nozzle differ from those in your usual garage.[7]
Another way to avoid misfuelling mistakes and potentially costly bills is to add a fuel reminder sticker beside your fuel cap, nudging you to use the correct fuel type when you fill up.[7]
If you own a diesel vehicle, you can also buy a device for the filler neck that makes it harder for the narrower petrol nozzle to fit.[7]
What is the cost of putting the wrong fuel in your car?
The cost of misfuelling your vehicle depends on the size of your car, its engine size, and whether you have started the engine and driven off.
Calling a fuel recovery specialist or breakdown service can average £190 if you haven’t started the engine.[11]
The cost could be much higher if you have started the engine and driven your car. In the worst-case scenarios, the repair could cost up to £5,000. However, this depends on the damage caused.
Ageas is one of the few insurers that have added accidental misfuelling cover to our breakdown cover. See what else we include in Ageas breakdown cover, powered by the RAC.
Most common questions
How long does it take to drain the wrong fuel from your vehicle?
It can take a few minutes or several hours, depending on how much fuel you put in the car and its fuel system and engine type.[1]
Can I drain my car’s system myself?
The answer is best not. Doing it in a station forecourt could be risky, whereas fuel recovery specialists receive training to work safely on them..[1]
Can the wrong fuel damage the engine?
Yes, especially if you put petrol in a diesel car. If you start the ignition, the damage can be worse than if you didn’t.[1]
Does putting E10 in an incompatible vehicle cause damage?
It does minimal harm if you do it occasionally. Your car or van will continue to work, although the corrosive bioethanol may damage internal parts over time.[1]
You can also add E5 to the rest of the E10 tank to reduce the effect of putting E10 in the wrong vehicle.
How much of the wrong fuel can damage a car?
This depends on whether you put petrol in a diesel car.
If you add a few drops of the incorrect fuel into your car, you may get away with it but it’s a risk.[2]
It’s vital not to turn the ignition on, as it primes the fuel system and will worsen things if you drive off.
Does car insurance over the costs of misfuelling?
Many insurers do not cover it, although Ageas Car Insurance includes wrong fuel cover as standard. We’ll pay to drain and flush your fuel tank and any damage to your engine directly caused by accidentally putting the wrong fuel in your car. We don’t cover replacement fuel.
Sources
[1] https://www.rac.co.uk/drive/advice/know-how/wrong-fuel-recovery
[2] https://www.theaa.com/breakdown-cover/advice/wrong-fuel-advice
[3] https://www.autoexpress.co.uk/car-news/95327/wrong-fuel-a-guide-on-what-to-do-if-you-put-petrol-in-a-diesel-car
[4] https://www.theaa.com/breakdown-cover/advice/wrong-fuel-advice
[5] https://www.autoexpress.co.uk/car-news/95327/wrong-fuel-a-guide-on-what-to-do-if-you-put-petrol-in-a-diesel-car
[6] https://www.rac.co.uk/drive/advice/know-how/wrong-fuel-recovery/#:~:text=rules%20for%20towing-,Wrong%20fuel%20in%20your%20car%3A%20the%20symptoms,slower%20than%20usual%20acceleration
[7] https://www.theaa.com/sitecore-cd/breakdown-cover/advice/wrong-fuel-advice/#:~:text=what%20to%20do%20when%20you%20put%20the%20wrong%20fuel%20in%20your%20car
[8] https://www.rac.co.uk/drive/advice/know-how/wrong-fuel-recovery/#:~:text=fixing%20your%20car%20after%20misfuelling
[9] https://www.theaa.com/breakdown-cover/advice/wrong-fuel-advice
[10] 2.1.1 Distillation – https://www.racfoundation.orgassets/rac–foundation/content/downloadables/Readdressing_the_balance_between_petrol_and_diesel_demand_Nick_Vandervell_September_2015.pdf
[11] https://www.rac.co.uk/drive/advice/know-how/wrong-fuel-recovery/#putting-diesel-in-a-petrol-car
[12] https://www.autoexpress.co.uk/car-news/95327/wrong-fuel-a-guide-on-what-to-do-if-you-put-petrol-in-a-diesel-car
[13] https://www.whatcar.com/advice/owning/what-to-do-if-you-put-the-wrong-fuel-in-your-car/n1131
[14] https://www.gov.ukguidance/e10-petrol-explained
