ECT

Scan Tool Range -40°C to 120°C (-40°F to 250°F): The ECT sensor is a thermistor that changes internal resistance as temperature changes. The PCM monitors a high signal voltage when the sensor is cold (internal resistance high) and interprets that voltage as a cold engine. The voltage signal decreases as the sensor becomes warm (internal resistance decreases) and the PCM interprets the lower voltage as a warm engine.