How to Tighten a Gas Capby Leonardo R. Grabkowski
An improperly tightened gas cap can cause gas fumes to leak from the tank, which can lead to a "Check Engine" light appearing in your odometer cluster. Properly tightening a gas cap after filling up your vehicle with fuel is necessary to prevent this. You can follow a specific procedure to ensure your gas cap is properly tightened.
Turn your car's engine off. Pull the fuel door release lever if your car has a locking fuel door.
Open the fuel door and unscrew the gas cap. Pump your gas. Don't top off the tank. Stop pumping as soon as the automatic shut-off kicks in.
Place the gas cap onto fuel port. Push it down firmly and turn it clockwise until you hear three clicks. This ensures the gas cap is properly tightened.