Engine Coolant Temperature (ECT) Sensor
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2000 Nissan Xterra, 2000 Nissan Sentra, 2000 Nissan Quest, 2000 Nissan Pathfinder, and 2000 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.
ECT sensor is installed in coolant inlet housing or intake manifold coolant passage. Sensor senses changes in temperature by monitoring resistance of a thermistor. As temperature increases, thermistor resistance decreases.
Sensor sends temperature information to ECM for air/fuel mixture, timing and idle speed control. During warm-up from cold start, ECM increases fuel enrichment to maintain engine performance. As engine temperature increases, ECM gradually decreases fuel enrichment until engine reaches normal operating temperature.