2000 Ford Focus Owner's Manual - Page 218

Maintenance and care Fuel filler cap If the Check engine indicator comes on and stays on when you start the engine, the fuel filler cap may not be properly installed. Turn off the engine, remove the fuel filler cap and reinstall it being careful to align the cap properly. If you must replace the fuel filler cap, replace it with a genuine Ford or Motorcraft part. The emission system performance may be adversely affected and the customer warranty may be void for any damage to the fuel tank or fuel system if a genuine Ford or Motorcraft fuel filler cap is not used. The fuel system may be under pressure. If the fuel filler cap is venting vapor or if you hear a hissing sound, wait until it stops before completely removing the fuel filler cap. Otherwise fuel may spray out and injure you or others. If you do not use the proper fuel cap, the pressure in the fuel tank can damage the fuel system or cause it to work improperly in a collision. Fuel filler cap lock (if equipped) Your vehicle may be equipped with a locking fuel filler cap. When fueling your vehicle: 1. Turn the engine off. 2. Open the fuel filler flap. 3. Unlock the fuel filler cap, using the key and turn cap counterclockwise to remove. 4. To close, turn the cap clockwise until it clicks. Refer to the previous section Fuel filler cap for additional information. 218