You never thought it would happen but there it is, you put diesel in a gas engine.

Well, what’s happened has happened, the main question is what should you do next?

This article will give you some advice that will hopefully get you out of trouble and save some nerves, the engine, and some serious money.



If you’ve put diesel in a gas engine, you’re at risk of causing serious damage to the engine and other systems (fuel injection system, ignition system, catalytic converter, etc).

I’m mentioning this as some drivers that lack car knowledge may see this problem as a minor one and get the idea that they can start the engine and continue driving. They simply won’t think of the problem as that much of a fuss.

The sad truth is that for one moment of negligence and further persistence you can end up paying hundreds of dollars or euros on repairs. Not to mention the lost time as these repairs are mostly very time-consuming.

To simplify, realize that you’ve made a mistake that will have serious consequences unless you follow the right procedure.




Panic is the arch-enemy of reasoning in any situation. The same goes if you put diesel in a gas engine.

Yes, you’ve made a mistake but it can be fixed which is the most important thing. You will lose time, have that in mind immediately. If you’re wise enough, you’ll lose a bit of money but not that much.

On the other hand, if you panic and let’s say, jump in the car, start the engine, and try to drive, you may cause serious damage to the car or endanger yourself or your passengers.

The same goes for any kind of improvisations you may try in order to fix the problem as soon as possible.

The best thing, by far, that you can do is to keep a cold head and follow the procedure. It will save the engine, you’re nerves, and your wallet.




Once you’ve realized that you’ve put diesel in a gas engine, don’t, under any circumstances try to start the engine.

Ask someone to help you push the car over to the parking lot of the fuel station or some other convenient place. Here you won’t disturb anyone and can call for help.

If you do try to start it, you’re opening a gateway to a lot of problems that are both complicated and expensive to fix. Have this mind if you get tempted to do so.

When the engine is started with the wrong fuel, it gets inside the whole fuel injection system and the engine. The outcome is dismantling the whole system (taking off the gas tank, fuel lines, fuel injectors, filters, and else), cleaning, rinsing, or replacing them and returning everything back.

As mentioned, a time-consuming and expensive job.

Opposed to this is emptying the gas tank which is a much easier and cheaper procedure. That is if you don’t start the engine.

Once you’ve noticed you’ve made a mistake, best put the ignition key away as you won’t need it for some time.




If you hopefully realized the mistake on time and didn’t start the engine, the first to do is get rid of the mixed fuel from the tank.

Easier said than done because gas tanks are built in such a way that pouring is easy while getting the fuel out is hard.

Two main reasons for this:

  • The gas tank gets fuel through a filler tube connected to it. This is the tube where you put the gas pistol inside. In most cases, it’s curved and has a safety, rollover valve that stops gas from coming out.
  • You need suction force to get the fuel out. The tank is at a lower point than the filler tube and gas cap (which is pretty much the only access point in that situation).

Nevertheless, it is all doable in a DIY manner given you have the proper tools. This means a container (like a spare fuel can), and a manual fuel pump (not electrical) with a longer hose connected to it.


I must mention that this should be done if there’s no other possible way and professional help isn’t available. If you decide to do so, practice extreme caution. Fuel is not to be played around with.

The basic principle is to open the gas tank cap, push in the hose of the pump as much as possible and pump out the fuel into the container. This is also called siphoning the gas tank.

The point is to get out as much of the contaminated fuel as possible. On this part, it’s good to know how much you poured until you noticed the mistake.

Honestly, it’s not rocket science but bigger issues are:

  • This usually happens at the gas station where there might not be a convenient nor safe place to do this. Nobody will be happy with pouring fuel in the open near a gas station.
  • Most drivers don’t have a spare fuel can and a manual fuel pump at hand. If there’s luck, the gas station may have these available. But sometimes the filler tube is so curved and the rollover valve on the gas tank is so stubborn that it takes a lot of time, persistence, and nerves to get the hose inside.

So, although this seems easy, the truth is it mostly ends in failure or quitting.

If you can, best call professional help. The car will be town away to a workshop and the job will be done under safe conditions.

The other option is that they’ll have proper tools to safely do it on-site (like with mobile fuel pumps or being able to drain the gas tank).

Besides this, they will dispose of the old fuel in a proper and ecological way as it is useless because of the diesel-gas mixture.

It may cost more, but taking into account the possible consequences, especially if you’re not good at repairing cars, it will be cheaper in the long run.

For more information about how to fix your car properly, click here.




Now once the wrong fuel is out, push the car back to the gas station and fill the tank up with the right fuel.

Know that a small amount of contaminated fuel will probably be leftover in the gas tank. Especially if it was removed with a fuel pump and via the filler tube.

But if done properly, most of it should be pumped out. Furthermore, filling up the gas tank will dissolve the leftover contaminated fuel to an acceptable level.

Don’t be surprised if you get a bit of engine knocking, stuttering, or white exhaust smoke. This is because leftover contaminated fuel may reach the engine. If this happens, it should last only for a couple of seconds.

If it lasts longer and there are more severe symptoms, stop the car as soon as possible and call for help.



Awareness and caution are some of the most important factors while being a driver.

As mentioned, the sad truth is that driving is a skill where a moment of inadvertency has serious consequences.

Putting diesel in a gas engine is perhaps one of the most annoying and nerve-racking ones. A seconds mistake and a simple mix-up of the gas pistols and you’re in for some serious trouble.

From lost time and trying to pump out the fuel, to waiting for help besides the car. From paying a smaller amount of money to get the wrong fuel out of the tank, to paying a small fortune to clean and rinse the whole system.

Having that in mind, the best advice is prevention. Always pay attention when pouring fuel.

Check the writing on the pump. Don’t text or talk on the phone when choosing the gas pistol. Don’t stare around, watch what you’re doing.

Last line of defense: check the receipt after you’ve paid (if you got one) and make sure the fuel type is right.

If you’ve made a mistake, keep a cool head. Don’t start the car and remember the tips you read here and get yourself out of trouble with the least possible consequences.

Remember these tips even if its’ vice versa, if you put gasoline in a diesel engine. The principle for getting out of trouble is basically the same.



Written by: Sibin Spasojevic


Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com

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