1998 Chevrolet Astro Owner's Manual - Page 146

Malfunction Indicator Lamp (Service Engine Soon Light) NOTICE: If you keep driving your vehicle with this light on, after a while, your emission controls not may be work as well, your fuel economy may not as good and your engine may not runsmoothly. as This could lead to costly repairs that may not be covered by your warranty. This light should come on, as a check to show you it is working, when the ignition ison and the engine is not running. If the light doesn'tcome on, have it repaired. This light will also come on during a malfunction in one of two ways: 0 1 SERVICE ENGINE SOON Your vehicle is equipped with a computer which monitors operation of the fuel, ignition and emission control systems. This system is called OBD I1 (On-Board Diagnostics-Second Generation) and is intendedto assure that emissions are at acceptable levels for the life of the vehicle, helpingto produce a cleaner environment. The SERVICE ENGINE SOON light comes on to indicate that thereis a problem and service is required. Malfunctions often will be indicated the by system before any problem is apparent. This may prevent more serious damage to your vehicle. This system is also designed to assist your service technician in correctly diagnosing any malfunction. 0 Light Flashing-- A misfire condition has been detected. A misfire increases vehicle emissions and may damage the emission control system on your vehicle. Dealer or qualified service center diagnosis and service may be required. Light On Steady-- An emission control system malfunction has been detectedon your vehicle. Dealer or qualified service center diagnosis and service may be required. 2-62