Engine Coolant Temperature Sensor
The engine coolant temperature sensor is mounted in a coolant passage located in the cylinder head. The engine coolant temperature sensor is a thermistor-type sensor. A thermistor resists the flow of electricity similar to a resistor; however, the resistance of a thermistor increases as temperature decreases. The thermistor produces a high resistance of 93,000 at -40°F (-40°C) at a low temperature, while a high temperature causes a low resistance of 65 ohms at 248°F (140°C).
The following chart lists the resistance of the inlet air temperature sensor and coolant temperature sensor as compared to temperature. The sensor resistances are identical for the IAT and ECT. See Fig 1 .