Ford 2003 Explorer Owner's Manual page 176

Maintenance and Specifications
• Illumination of the charging system, temperature, or "Check Engine"
light in the instrument panel.
Exhaust leaks may result in harmful and potentially lethal fumes
entering the passenger compartment.
It is unlawful to intentionally remove an emission control device or
prevent it from working. Information about your vehicle's emission
system is on the Vehicle Emission Control Information decal located on
or near the engine.
On board diagnostics (OBD-II)
Your vehicle is equipped with a computer that monitors the engine's
emission control system. This system is commonly known as the On
Board Diagnostics System (OBD-II). This OBD-II system protects the
environment by ensuring that your vehicle continues to meet
government emission standards. The OBD-II system also assists the
service technician in properly servicing your vehicle. When the Check
Engine/Service Engine Soon light illuminates, the OBD-II system has
detected a malfunction. Temporary malfunctions may cause your Check
Engine/Service Engine Soon 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 securely tightened.
These temporary malfunctions can be corrected by filling the fuel tank
with good quality fuel and/or properly tightening the fuel cap. After three
driving cycles without these or any other temporary malfunctions
present, the Check Engine/Service Engine Soon 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.
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
It may be a legal requirement in your area to pass an I/M test of the
on-board diagnostics system. If the system or battery has just been
serviced, the on-board diagnostic system is reset to a "not ready for I/M
test" condition. To ready the system, allow the vehicle to sit for at least
eight hours without starting. Then, start the engine and complete the
following driving cycle:
1. Drive on an expressway or highway for at least 10 minutes.
176