Posts Tagged: loose gas cap cause a check engine light

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

How does a loose gas cap cause a check engine light? Vehicles are equipped with an evaporative emissions system that captures fuel vapors as you fill your tank. Venting fuel vapors into the air causes air pollution and smog. How does the evaporative emissions system work? As you fill your tank with fuel, vapor pressure builds up in the tank, pushing the fuel vapors into a canister filled with activated charcoal. The charcoal absorbs the fuel vapor and stores it temporarily. After filling you install the gas cap and start … Read More