FORD 2002 Focus v.2 - Manual (Page 11)

Instrument Cluster
11
The Check engine indicator light
illuminates when the ignition is first
turned to the ON/RUN position to
check the bulb. 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 driveable
and will not require towing.
What you should do if the check
engine light illuminates
Light turns on solid:
This means that the OBD II system
has detected a malfunction.
Temporary malfunctions may cause
your Check engine light to
illuminate. Examples are:
1. The vehicle has run out of fuel.
(The engine may misfire or run
poorly).
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 good quality fuel and/or
properly installing and securely
tightening the gas cap. After three
drive cycles without these or any
other temporary malfunctions
present, the Check engine 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.