FORD 2003 Mustang v.3 - Manual (Page 187)

If the Check Engine/Service Engine Soon light
remains on, have your vehicle serviced at the first
available opportunity.
Readiness for Inspection/Maintenance (I/M)
testing
In some localities, it may be a legal requirement to
pass an I/M test of the on-board diagnostics system.
If your “Check Engine/Service Engine Soon” light is
on, refer to the description in the Warning lights
and chimes section of the Instrument cluster
chapter. Your vehicle may not pass the I/M test with
the “Check Engine/Service Engine Soon” light on.
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.
Maintenance and Specifications
187