Accidentally Overfilled Gas Tank: What To Do? (Explained!)

As a car driver, you might hear that click on the gas hose when filling up your gas tank. This click is telling you to stop filling because it is already full. However, many car drivers still ask what would happen if you keep on overfilling your gas tank even after hearing that gas hose click. 

So what can you do if you have accidentally overfilled your gas tank? If you have overfilled your gas tank, you can just run it at idle for a while as soon as you can and take the fuel cap off. Remember to not fill the gas tank to the top of the container. Use the fuel nozzle cut-off so that it can tell you that it is complete enough. 

Many car drivers do this because they want their money’s worth and are putting as much gas as it can fit. But this is not recommended. If you overfill your gas tank, it can cause severe damage to your vehicle. 

And you might have to spend money on some repairs. So this article is made regarding this matter. 

This article will talk about what would happen if you overflow your gas and what you would do if you had an overfilled gas tank. So let us start. 

Accidentally Overfilled Gas Tank

Is It Bad If Your Gas Tank Overflows?

It can be. Your engine has a complex and closed-circuit system, and it will trap and then burn the fumes coming from your gas tank. If you often overflow your regular or diesel fuel tank, the EVAP system made to do the process on excess gasoline vapor will be compromised. 

This can distort the performance of your car. As a result, you will have a check engine light, and in addition, you will be going to spend some money on the repair of your vehicle. 

What Happens If You Overfill Your Gas Tank?

Overfilling your gas tank can damage your engine, and you will be spending a lot of money on your pump. The gas stations have a vapor recovery system. This system will feed gas vapors and gasoline from the pump back into the gas station tank if you overfill. 

This is to have protection for the environment and your vehicle. If you put too much gas in your tank, this can cause the fuel vapor recovery system to put the extra gas you have just paid for back into the gas pump. It can also be possible that the vapor recovery system is broken in the pump. 

As a result, it will cause the gas to spill out more out of your vehicle and the gas nozzle while overfilling. This means that you will be spending even more money. 

So the best decision is not to overfill your vehicle because it can cost you somewhere around two hundred dollars ($200) to one thousand five hundred dollars ($1,500). So do not overfill your gas tank and stop if you hear the hose click. 

Can Your Car Explode From Too Much Gas?

No, vehicles would be pretty unlikely to explode. They explode in movies, but they have explosives on them. If you overfill your fuel tank, the gas that will not fit in the gas tank will overflow and go into the ground. 

If it is petrol gas, you might be in a difficult situation. The liquid petrol might not be too bad, but it will quickly evaporate. A petrol air mixture is also flammable. 

If there is even a tiny spark, it can set it off. If you have a very hot exhaust, it can set it off too. Diesel is a lot safer. It does not evaporate quickly and is hard to light – you can drop a lit cigarette in it and usually get away with it. 

So what will happen is there will be a puddle of fuel in your vehicle. So you have to take that spill kit fast and then ensure that no one near that is smoking or might be running an engine. Clean the fuel and then drive away. 

Petrol that is mixed with air can explode, and the fumes evaporate. So your vehicle will not be harmed because the fuel in the tank has no air, so it will not explode. However, the heat will make the evaporation even faster, and this can trigger the fire. 

Your vehicle will be on fire. A vehicle contains a lot of plastics, oil, and rubbers, and it can and will burn. 

There might be some tiny explosions, but it will be a burning car, not an explosion, as you see in films. Diesel will not even explode. If you ignite it, the vehicle will burn with flames.

Overfilled Gas Tank

How Do You Know If You Overfilled The Gas Tank?

For anyone who has filled up their tank, you might notice a click in the nozzle. This sound is telling you that your gas tank is complete and that you should stop overfilling. If you hear this sound, this is coming from the nozzle right if the fuel flow will stop. 

Many car drivers do not hear the sound, and they would not notice it constantly and ignore the sound. But you should not ignore it. It is the way of your vehicle to tell you that the gas tank is complete and that you should stop filling the gas tank. 

Can Overfilling The Gas Tank Cause The Check Engine Light To Come On?

If your fuel overflows, the fuel system will trigger the vapor recovery and the tank vet to become flooded with liquid fuel. The flooding on the vent system will make the computer sense that there is a problem in the fuel tank. This will then clean the valve function, and then it will set a code. 

It will then turn on the check engine light. You have to diagnose your check engine light and any code that is received from the memory. You also have to drive your vehicle and check if the code will return. 

If the light will not come back on, you did not have any damage when you overfilled your fuel tank. But if the light turns on again, one of the fuel tank vapor system components might have to be replaced. It would also be better to consult a mechanic. 

What To Do If You Overfill Your Gas Tank?

If you have overfilled your gas tank, you can just run it at idle for a while as soon as you can and take the fuel cap off. Remember to not fill the gas tank to the top of the container. Use the fuel nozzle cut-off so that it can tell you that it is complete enough. 

If there is fuel on the tank breather carbon filter canister, it will give a code and prevent the engine from running. With that, you might also have to replace your canister. 

This is not a problem, though. If you have an old vehicle, you can directly pour some water on the spilled fuel, and it will splash on the floor. You can mop it up.

What To Do When Your Gas Tank Overflows?

You have to turn off the pump if your gas tank is overflowing. This is more ideal before the overflow happens. All the modern fuel pumps have a special valve so that this can be prevented. 

This can be a dangerous situation. You might also have damaged your emission vapor control system, which is located on top of the average maximum fuel level. So you then have to pay for the fuel that has been spilled and then tell the attendant. 

You also have to be mindful to avoid sparks or flames for the next few days. You have to wait until the fuel level goes back to its normal state. 

After the next few days, if you still have some fuel left and you can still smell it, you might have to do a replacement with your vapor canister inside your fuel tank. This can cost you money, so it is wise not to overflow your gas tank. 

Can I Start My Car If Gas Overflows?

Yes, you can. Gasoline would evaporate very quickly, and there should be no danger of that. A spilled gas can be hastily gone. 

Many people have been driving their vehicles even if they have overflowed their gas. But there is still the possibility of damages. So you still have to weigh the options and monitor the situation first.


In summary, topping your gas is an everyday activity for all car drivers. It is now considered a regular thing, but a problem can still be encountered in overfilling your gas tank. 

You must not overfill your gas tank because it can cause you damages and some significant repairs. If you hear the click on the nozzle, stop right away because your gas tank is already full.

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more