1999 Ford F250 Owner's Manual - Page 9

Instrumentation What you should do if the Check Engine/Service Engine Soon light illuminates Light turns on solid: This means that the OBD I system has detected a malfunction. Temporary malfunctions may cause your 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. These and other temporary malfunctions can be corrected by filling the fuel tank with good quality fuel. 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. Under engine misfire conditions, excessive exhaust temperatures could damage the catalytic converter, the fuel system, interior floor coverings or other vehicle components, possibly causing a fire. Service engine soon (California only) Your vehicle is equipped with a SERVICE computer that monitors the engine's ENGINE emission control system. This SOON 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. The Service Engine Soon indicator light illuminates when the ignition is first turned to the ON position to check the bulb. If it comes on after the engine is started, one of the engine's emission control systems may be malfunctioning. The light may illuminate without a driveability concern being noted. The vehicle will usually be drivable and will not require towing. 9