Help! I’ve put the wrong fuel in my car

Here’s what to do if it’s not happened to you before.

You might think that putting the wrong fuel in your car is a rare occurrence. After all, it probably hasn’t happened to you or anyone you know. However, it’s so common these days, it’s got its own name: misfuelling. Is it as bad as it sounds? And is it irreversible?

Driving a diesel car with petrol in the tank can be catastrophic. Diesel engines run differently to petrol ones, and once petrol has been drawn through the system, it will stop working. And putting it right can cost thousands. This is usually the worst-case scenario though, and you’d have to be really hammering along to get to that state.

But if you’ve not noticed your mistake, your car will soon tell you with its juddering, lack of vroom or a warning light on your dashboard. Things could still be salvageable at this point, but it will be far from cheap.

Putting diesel into a petrol engine isn’t quite as severe and not so common. This is mostly due to the design of the nozzle at the pump – a diesel dispenser is wider than most petrol tank pipes, so you do need to be quite persistent to manage it. If you do, the diesel will stop your petrol engine working and leave the internal workings greasy, but it won’t damage it badly.

If you do ever misfuel your car, hopefully you’ll notice while you’re actually doing it or as soon as you put the pump back into its slot. At that point you are safe, and it’s easy to sort out if you know what to do.

Once you’ve got any swearing out of your system, go into the petrol station and tell the attendant what’s happened. They’ve seen it all before and probably have a well-oiled plan of action. They might cone off your car to save you having to push it out of the way, have a dedicated call-out service or give you a number to phone.

What happens next?

Much like a breakdown recovery service, the fuel engineer will come and deal with things at the car – they won’t need to tow it away.

The wrong fuel is drained from your tank and the system will be flushed through, ready for it to be filled with the correct type of fuel and for you to get on your way.

If you’ve driven your car any distance, a drain and flush could still work. But the risk of more serious damage increases – and so do the repair costs.

How much does misfuel recovery cost?

It all depends on the company and if things can be put right at the petrol station. If things are more advanced and your car’s come to a halt once you’re driving, the costs start to mount. It could need towing and work done at a garage. And then there’s the cost of new parts.