Engine Coolant Temperature Sensor

PCM uses the Engine Coolant Temperature (ECT) sensor to monitor engine coolant temperature. ECT sensor is a thermistor (variable resistor) wired in series with a fixed resistor inside PCM. A 5-volt reference is supplied and monitored by PCM. Sensor resistance, which changes according to coolant temperature, is converted to a temperature reading by PCM. High coolant temperature causes low resistance and low coolant temperature causes high resistance. PCM uses this information for fuel control, timing, air management, idle speed and closed loop fuel control. For component locations, see Figure or Figure .