Ford 2003 Mustang Owner's Manual page 177

If the vehicle's powertrain system or its battery has
just been serviced, the on-board diagnostics system
is reset to a "not ready for I/M test" condition. To
ready the on-board diagnostics system for I/M
testing, a minimum of 30 minutes of city and
highway driving is necessary as described below:
First, at least 10 minutes of driving on an
expressway or highway.
Next, at least 20 minutes driving in stop-and-go,
city-type traffic with at least four idle periods.
Allow the vehicle to sit for at least eight hours
without starting the engine. Then, start the engine
and complete the above driving cycle. The engine
must warm up to its normal operating temperature.
Once started, do not turn off the engine until the
above driving cycle is complete.
EXTERIOR BULBS
Replacing exterior bulbs
Check the operation of the following lamps
frequently:
Headlamps
Tail lamps
Brakelamps
High-mount brakelamp
Turn signals
Backup lamps
License plate lamp
Do not remove lamp bulbs unless they will be
replaced immediately. If a bulb is removed for an
extended period of time, contaminants may enter
the lamp housings and affect performance.
Maintenance and care
177