Why does a loose gas cap trigger a check engine light?

So, you're driving, and your check engine light pops up. Concerned but wanting to be responsible, you google what might have caused your light to turn on. You're shocked to learn that several sources state a loose gas cap can trigger a check engine light. So, what's the reason? 

Let's start by stating that, yes, it's possible that a loose gas cap can cause your vehicle to trigger a CEL (Check Engine Light). The gas cap keeps dirt and debris from getting into your gas tank. As part of your EVAP (Evaporative Emissions control) system, it is responsible for preventing vapors from escaping your fuel tank. Not properly containing these harmful vapors ruin your fuel efficiency and the environment as well. Your wallet and the world take damage.

Even in these expensive times we're in now; we frequently head to the gas station to fill up. These repeat trips of twisting your gas cap open and closed again will cause the seal in your cap to wear, where the problem arises. If the fuel cap isn't tightening as it should, or you smell gasoline, this could let you know your seal is weakening even if you don't have a check engine light appear.

There are countless reasons your check engine light could appear, but before you panic, always keep in mind that the gas cap could be the culprit. A trusted mechanic can replace a cracked gas cap or one with a weakened seal.   For any automotive needs, bring your vehicle to a shop with ASE-certified mechanics such as Ferber's Tire and Auto for an inspection today!