FORD 2003 Crown Victoria v.1 - Manual (Page 200)

5. Turn the filler cap clockwise 1/8 of a turn until it stops.
“Check Fuel Cap” illuminates when the ignition is turned to the ON
position to ensure your bulb is working. When this light turns on, check
the fuel filler cap. Continuing to operate the vehicle with the Check Fuel
Cap light on, can activate the Service Engine Soon warning. When the
fuel filler cap is properly re-installed, the light(s) will turn off after a
period of normal driving. It may take a long period of time for the
system to detect an improperly installed fuel filler cap.
If you must replace the fuel filler cap, replace it with a fuel filler
cap that is designed for your vehicle. The customer warranty may
be void for any damage to the fuel tank or fuel system if the
correct 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 filler cap, excessive pressure or
vacuum in the fuel tank may damage the fuel system or cause
the fuel cap to disengage in a collision, which may result in possible
personal injury.
Choosing the right fuel
Use only UNLEADED FUEL. The use of leaded fuel is prohibited by law
and could damage your vehicle.
Do not use fuel containing methanol. It can damage critical fuel system
components.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based compounds containing MMT.
Repairs to correct the effects of using a fuel for which your vehicle was
not designed may not be covered by your warranty.
Maintenance and Specifications
200