FORD 2002 F-150 v.2 - Manual (Page 11)

Many lights will illuminate when you start your vehicle to make sure the
bulb works. If any light remains on after starting the vehicle, have
the respective system inspected immediately.
Service engine soon
Illuminates briefly to ensure the
system is functional. If it comes on
after the engine is started, one of
the engine’s emission control
systems may be malfunctioning. The light may illuminate without a
driveability concern being noted. The vehicle will usually be drivable and
will not require towing.
Light turns on solid:
Temporary malfunctions may cause the light to illuminate. Examples are:
1. The vehicle has run out of fuel.
2. Poor fuel quality or water in the fuel.
3. The fuel cap may not have been properly installed and securely
tightened.
These temporary malfunctions can be corrected by filling the fuel tank
with high quality fuel of the recommended octane and/or properly
installing and securely tightening the fuel cap. After three driving cycles
without these or any other temporary malfunctions present, the light
should turn off. (A driving cycle consists of a cold engine startup
followed by mixed city/highway driving.) No additional vehicle service is
required.
If the light remains on, have your vehicle serviced at the first available
opportunity.
Light is blinking:
Engine misfire is occurring which could damage your catalytic converter.
You should drive in a moderate fashion (avoid heavy acceleration and
deceleration) and have your vehicle serviced at the first available
opportunity.
Under engine misfire conditions, excessive exhaust temperatures
could damage the catalytic converter, the fuel system, interior
floor coverings or other vehicle components, possibly causing a fire.
SERVICE
ENGINE
SOON
Instrument Cluster
11