2010 Cadillac STS Owner's Manual - Page 366

While refueling, hang the tethered fuel cap from the hook on the fuel door. { WARNING: Fuel can spray out on you if you open the fuel cap too quickly. If you spill fuel and then something ignites it, you could be badly burned. This spray can happen if the tank is nearly full, and is more likely in hot weather. Open the fuel cap slowly and wait for any hiss noise to stop. Then unscrew the cap all the way. Be careful not to spill fuel. Do not top off or overfill the tank, and wait a few seconds after you have finished pumping before removing the nozzle. Clean fuel from painted surfaces as soon as possible. See Washing Your Vehicle on page 6‑111. When replacing the fuel cap, turn it clockwise until it clicks. Make sure the cap is fully installed. 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 4‑62. The CHECK GAS CAP message will appear on the Driver Information Center (DIC) display if the fuel cap is not reinstalled properly. See DIC Warnings and Messages on page 4‑76 for more information. 6-10