DeAnn Owens
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What Happens If You Lose Your Gas Cap?

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gas pump refuel tank car empty
Photo: The News Wheel

Your gas cap is one of those car parts you likely don’t give much thought to outside of your trips to the gas station. But if you suddenly find yourself lacking yours, you might start to wonder how important it is to your car. While you can still drive your car without a gas cap, it is inadvisable to do so for several reasons.


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“Sealing off the fuel tank with the gas cap helps your fuel system maintain proper pressure, which in turn helps your car operate smoothly,” explains How Stuff Works writer Cherise Threewitt.

So, without a gas cap, are you destined for a breakdown? Not necessarily, but you will have to deal with some minor inconveniences.

“You might lose a little gas, more likely due to evaporation than to actual spillage, because the filler neck helps prevent sloshing,” Threewitt reports.

Your fuel economy will diminish a bit, too, and because the gas tank is more exposed than usual, it’s at risk for debris or moisture. Depending on the tech in your car, the missing gas cap can influence your car’s performance because it senses something is wrong. If your car is scheduled for an emissions test, make sure you replace the gas cap before your test day or your car will fail.

Although driving without a gas cap will not greatly impact your driving experience, it’s not ideal. You do not want your fuel economy to decrease or make Mother Nature or other people suffer with the gas spilling from your tank.

Thankfully, replacing a gas cap is one automotive repair that is cheap and easy to do yourself. Refer to your owner’s manual for the correct model or consult the parts department at your local dealership for advice.


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