Why would the low coolant light come onon a 2000 Sable?

Answer 1

In the engine compartment, on the left side of the engine is the coolant reservoir. In the coolant reservoir, there is a sensor at the bottom of the reservoir. This sensor is supposed to let you know when you are low on coolant, but can also become defective, and give you a "false-positive" reading. The only way to know this is to check your coolant when the low coolant light comes on. If there is a significant decrease in coolant, you may have a problem in the cooling system , but if you don't, chances are the sensor isn't working. If the sensor is the problem, you can unplug it from the coolant reservoir, by unscrewing the two screws holding the reservoir to the car's inside firewall, then tilting the back of the coolant reservoir forward until you see wiring coming from the bottom of the reservoir, which is the plug for the low coolant sensor. Unplug the sensor, and the low coolant light won't come on anymore. However, you will now have to make sure you check your coolant level in the reservoir on a regular basis.