Engine Coolant Temperature (ECT) Sensor

ECT sensor is installed in the coolant inlet housing or intake manifold coolant passage. Sensor changes return voltage signal to PCM depending upon the resistance of a thermistor. PCM uses this information for varying air/fuel mixture, timing and for idle speed control. During warm-up from cold start, PCM increases fuel enrichment to maintain engine performance. As temperature increases, thermistor resistance decreases and the PCM gradually decreases fuel enrichment until engine reaches normal operating temperature.