If theService engine soonindicator remains on, have your vehicle
serviced at the first available opportunity. Although some malfunctions
detected by the OBD-II may not have symptoms that are apparent,
continued driving with theService engine soon
indicator on can
result in increased emissions, lower fuel economy, reduced engine and
transmission smoothness, and lead to more costly repairs.
Readiness for Inspection/Maintenance (I/M) testing
Some state/provincial and local governments may have
Inspection/Maintenance (I/M) programs to inspect the emission control
equipment on your vehicle. Failure to pass this inspection could prevent
you from getting a vehicle registration. Your vehicle may not pass the I/M
test if theService engine soon
indicator is on or not working
properly (bulb is burned out), or if the OBD-II system has determined
that some of the emission control systems have not been properly
checked. In this case, the vehicle is considered not ready for I/M testing.
If theService engine soon
indicator is on or the bulb does not
work, the vehicle may need to be serviced. Refer to the On board
diagnostics (OBD-II) description in this chapter.
If the vehicle’s engine or transmission has just been serviced, or the
battery has recently run down or been replaced, the OBD-II system may
indicate that the vehicle is not ready for I/M testing. To determine if the
vehicle is ready for I/M testing, turn the ignition key to the on position
for 15 seconds without cranking the engine. If theService engine
soon
indicator blinks eight times, it means that the vehicle is not
ready for I/M testing; if theService engine soon
indicator stays on
solid, it means that the vehicle is ready for I/M testing.
The OBD-II system is designed to check the emission control system
during normal driving. A complete check may take several days. If the
vehicle is not ready for I/M testing, the following driving cycle consisting
of mixed city and highway driving may be performed:
15 minutes of steady driving on an expressway/highway followed by
20 minutes of stop-and-go driving with at least four 30-second 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. If
the vehicle is still not ready for I/M testing, the above driving cycle will
have to be repeated.
2008 Town Car(tow)
Owners Guide (post-2002-fmt)
USA(fus)
Maintenance and Specifications
253
