Engine Coolant Temperature (ECT) Sensor

The ECT sensor is located on intake manifold, near thermostat housing. ECT sensor consists of a temperature dependent resistive metal strip. ECT sensor resistance changes as engine coolant temperature changes. See ECT SENSOR RESISTANCE  . ECM monitors ECT sensor resistance values and triggers enrichment circuits to extend injector on-time during cold starting and warm-up (a richer mixture at low coolant temperatures).

Default strategy for ECT sensor is to select a substitute value based on intake air temperature. Initial ECT sensor default value selected will increase to a pre-warm up value over a time period programed for each default. An ECT sensor fault may result in a fast idle condition on initial start-up until fully warm value is reached. There may be a hot engine restart problem. A fault is indicated by illumination of the MIL.