1999 Pontiac Montana Owner's Manual - Page 191

yellowblue It means that your engine coolant has overheated. If you have been operating your vehicle under normal driving conditions, you should pull off the road, stop your vehicle and turn off the engine as soon as possible. In "Problems on the Road," this manual shows what to do. See "Engine Overheating" in the Index. Malfunction Indicator Lamp (Service Engine Soon Light in the United States or Check Engine Light in Canada) Low Coolant Warning Light United States Canada Your vehicle is equipped with a computer which monitors operation of the fuel, ignition and emission control systems. United States Canada This system is called OBD II (On-Board Diagnostics-Second Generation) and is intended to assure that emissions are at acceptable levels for the life of the vehicle, helping to produce a cleaner environment. The SERVICE ENGINE SOON or CHECK ENGINE light comes on to indicate that there is a problem and service is required. Malfunctions often will be indicated by the 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. If this light comes on, your system is low on coolant and the engine may overheat. See "Engine Coolant" in the Index and have your vehicle serviced as soon as possible. 2-95