Why temperature sensor is used in vehicle?

The temperature sensor in automobile is used to measure the temperature of coolant, inlet air and exhaust gas oxygen sensor. It consists of a thermistor munted in a housing that is designed to be inserted in the coolant stream. A thermistor is made of semiconductor material whose resistance varies inversely with temperature. For example, at -40 degree a typical coolant sensor has a resistance of 100,000 ohms. The resistance decreases to about 70,000 ohms at 130 degree.