Misfuelling Mishaps: What To Do If You Put The Wrong Fuel In

Picture this. You’re on the way home from work and your fuel light illuminates. So you pull in to a filling station to top up your fuel, and you’re sure that you’ll be back on your route home in a matter of minutes. Almost on autopilot, you pull up to the pump, take the nozzle and put it into your car and start filling. You fill up half way…only to realise that you’ve put the wrong fuel in the car! Cue the panic! Here’s our guide on what to do next: 


Don’t worry!

Firstly, try not to worry, these things happen. In fact, more than 150,000 people a year admit to putting the wrong fuel in their tank, so you’re definitely not alone. Even the police get it wrong sometimes, with officers from across the UK misfuelling around 300 times in 2018, according to an article in The Telegraph.


Don’t start the engine.

This is an absolutely vital piece of information. Do not start your engine under any circumstances. Doing so can result in permanent damage which will mean expensive repair bills. Remove the keys from the ignition, or if your car has keyless start, keep the key away from the car if possible. 


Get help.

It sounds obvious, but try and get help. Make the petrol station staff aware of what has happened, and try and get some help to push your car away from the pump to a safe location, so that you’re not blocking the pump for other customers.  If you have breakdown cover, such as with the AA, RAC or Green Flag, then get in touch with them as soon as you can and explain the situation. 


Talk to your insurers.

You may need to talk to your insurance company to make them aware that a claim could be coming their way, particularly if you don’t have breakdown cover. 


What happens if you put petrol in a diesel car?

Misfuelling by putting petrol in a diesel tank can cause significant damage to the internal workings of your vehicle, even more so than if you put diesel in a petrol car. 

This is because diesel acts as a lubricant, whereas petrol does the opposite, increasing friction between parts in the diesel engine. That means that the more petrol is pumped through the engine, the more damage it will do, with High-pressure direct injection (HDi) diesel engines being particularly susceptible to damage caused by misfuelling. If you’ve started the engine, or the tank can’t be drained by a roadside breakdown mechanic, then you could end up needing new fuel pumps, injectors, pipes, filters, fuel tank, or even a whole new engine! 


What happens if you put diesel in a petrol car?

Although not as serious as putting petrol in a diesel car, filling your vehicle with diesel when it should be running on unleaded still has the potential to damage your car. 

When you start your engine, diesel will cover your spark plugs and the fuel system, which will most likely mean that the car misfires. It may also smoke, cut out or may not even start at all!

To avoid misfuelling in the first place, there are a number of things you can do. Remember to always read the label on the pump carefully before filling up your car, even if you think you’re using the correct fuel. Also consider putting a sticker identifying the correct fuel on the inside of the fuel cap. Alternatively, some manufacturers such as Ford have a system in place which prevents the wrong nozzle being entered into the filler cap, so if you’re a serial misfueller, you may want to buy a car which has such a system!

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