2003 Cadillac DeVille Owner's Manual - Page 280

When you put the fuel cap back on, turn it to the right (clockwise) until you hear a clicking sound. Make sure you fully install the cap. The diagnostic system can determine if the fuel cap has been left off or improperly installed. This would allow fuel to evaporate into the atmosphere. See Malfunction Indicator Lamp on page 3-50. The CHECK GAS CAP message in the Driver Information Center (DIC) will come on if the fuel cap is not properly reinstalled. Notice: If you need a new fuel be sure to get the cap, right type. Your dealer can get one for you. Ifyou get the wrongtype, it may not fit properly. This may cause your malfunction indicator lamp to light and may damageyour fuel tank and emissions system. See "Malfunction Indicator Lamp'' in the Index. Never fill a portable fuelcc..,ainer while it is in your vehicle. Static electricity discharge from the container can ignite the gasoline vapor. You can be badly burned and your vehicle damaged if this occurs.To help avoid injury to you and others: 0 Dispense gasoline only into approved containers. Do not fill a container while it is inside a vehicle, in a vehicle's trunk, pickup bed or on any surface other than the ground. Bring the fill nozzle in contact with the inside of the fill opening before operating the nozzle. Contact should be maintained until the fillin9 is complete. Don't smoke while pumping gasoline. @ 5-9