2001 Ford Mustang Owner Guide 3rd Printing - Page 10

Instrumentation 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. What you should do if the Service Engine Soon light illuminates Light turns on solid: This means that the OBD II 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. 3. The fuel cap may not have been properly installed and securely tightened. These temporary malfunctions can be corrected by filling the fuel tank with high quality fuel of the recommended octane and/or properly installing and securely tightening the gas cap. After three driving cycles without these or any other temporary malfunctions present, the 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 Service Engine Soon light remains on, have your vehicle serviced at the first available opportunity. Light is blinking: Engine misfire is occurring which could damage your catalytic converter. You should drive in a moderate fashion (avoid heavy acceleration and deceleration) and have your vehicle serviced at the first available opportunity. 10