Board Diagnostics System (OBD-II). The OBD-II system protects the
environment by ensuring that your vehicle continues to meet
government emission standards. The OBD-II system also assists your
authorized dealer in properly servicing your vehicle. When the
indicator illuminates, the OBD-II system has detected a malfunction.
Temporary malfunctions may cause the
indicator 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—the engine may misfire or run
poorly.
3. The fuel cap may not have been securely tightened. SeeFuel filler
capin this chapter.
4. Driving through deep water—the electrical system may be wet.
These temporary malfunctions can be corrected by filling the fuel tank
with good quality fuel, properly tightening the fuel cap or letting the
electrical system dry out. After three driving cycles without these or any
other temporary malfunctions present, the
indicator should stay off
the next time the engine is started. A driving cycle consists of a cold
engine startup followed by mixed city/highway driving. No additional
vehicle service is required.
If the
indicator 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 the
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 the
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 the
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.
2008 Expedition(exd)
Owners Guide (post-2002-fmt)
USA(fus)
Maintenance and Specifications
370
