FORD 2003 Mustang v.2 - Manual (Page 178)

4. To install the cap, align the tabs on the cap with
the notches on the filler pipe.
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.
Maintenance and Specifications
178