I filled up with the wrong fuel – what should I do? A practical guide

Pouring the wrong fuel into the car is – contrary to appearances – not so rare cases. It happens especially to people who often change their car or use their private and business cars alternately. Should we be concerned if we make a mistake at the distributor?

The mistake most often happens to people who fill up with diesel, because the tip from the petrol dispenser fits into the diesel filling hole, and the diesel tip is too big to pour diesel into a petrol car. In fact, the effect of a mistake depends only on two factors: the year of manufacture of the car and how much of the wrong fuel you put in.


Even a large amount of gasoline in a diesel tank can be imperceptible. The engine itself can handle it. We are talking about a situation where the proportions reach approx. 20-30 percent. the wrong fuel. I know a case where 1/3 of the diesel tank was gasoline and the car from 2017 drove without any problems, not even showing a decrease in power. Unfortunately, the exhaust gas treatment system, especially the DPF / FAP filter, may suffer from this. But that’s in the distant future.

The newer the diesel, the greater the risk of exhaust system failure, which can be very expensive. A few liters in a car from a year newer than 2010 (Euro 5 standard) may not hurt, but a dozen or so is. If the proportion exceeds 10-15%, then due to the high risk, it is better to call for help.

In older diesels, without DPF, gasoline is not harmful. As long as the engine is running, it can handle the wrong fuel. Common rail injection from the 1990s (first generation) is not much more demanding than ordinary injectors. Reacts more to fuel impurities than composition.

To sum up: if you poured gasoline into the diesel, but not much, then don’t worry. A few-year-old car can take it worse, but a dozen-year-old will go soooo, as if nothing had happened.


In the case of older, several-year-old petrol cars, the only effect of such a mistake will be stopping the engine or its uneven operation. A dozen or so percent of diesel will dirty the engine a bit, maybe the exhaust system, but it won’t hurt. A reduction in power or – in some cases – stalling of the engine is to be expected.

It’s worse in modern cars. The catalytic converter is at risk of failure, but also the precise injection system. Regardless of whether we have indirect or direct injection, a portion of diesel fuel greater than a few liters can be harmful. But not enough to panic. Call for help and drain the fuel.

The greatest risk concerns petrol cars equipped with a GPF filter, which is a fairly new and expensive solution. The sensitive injection system will also hit the bone. Pouring a small portion of diesel may not be noticeable, but a few liters will pay off in the long run.

To sum up: if you have a car manufactured before 2000, there are no serious concerns. In a car from around 2018-2019, a small portion of diesel fuel will not hurt either, but several liters per tank can. In cars produced from around 2018 and equipped with a GPF filter, such mistakes should be avoided.


Since this is a practical guide, not a theoretical one, I don’t mean to make you feel uneasy. So let’s focus on gasoline in diesel, not the other way around. First of all, you should think about what proportions the wrong fuel will be when you add the correct fuel to the full. Secondly, you should consider the consequences of interrupting the journey you have just embarked on. Third – how much is the car worth to you.

If the wrong fuel (petrol in diesel) is not more than 10-15%, you can fill up with the correct fuel and drive on, and after driving 100-200 km, refuel again. If you travel far, it is best to repeat it from time to time, on average every 100-200 km. It is good not to use full power and drive rather calmly, and also to react to the lights on the dashboard. If one of them catches fire, you should stop and call for help. Sometimes it’s better to get to your destination and think about solving the problem than to stand at the station and do it under stress.

The situation is slightly different in the case of a very modern car – let’s assume that it is not older than 2015. Then there is a risk of damage to the exhaust gas purification system. In an atypical model, with little popularity, it can be very expensive. I mean brands such as Mazda, Land Rover, Jaguar, Subaru, etc. Therefore, it is good to call for help and at least in this topic to sleep peacefully. If it’s just a little bit of the wrong fuel – up to a liter – then filling up with the correct fuel will solve the problem.


It is definitely worth using Assistance if you have purchased such insurance. You can also go to the gas station where you filled up and ask for help. Often people from a given region who know a mechanic work there. The car does not have to be towed, because with the appropriate knowledge and tools, the mechanic will drain the fuel on the spot. You can also call the nearest tow truck, which will take the car to a nearby workshop, where the fuel will be removed from the tank.

The last choice – if the car is just refueled and has not stopped while driving – should be an authorized service station. Not only will you pay a lot for the fuel removal service and there is rather no chance of getting in line before other customers, there is also a high probability of “finding another fault”.

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Audi maniac, owner of upgrademyaudi.net and big fan of Audi cars. Maps, firmware, car audio installer
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