DTC P0117: Engine Coolant Temperature Sensor Circuit Low Input Or DTC P0118: Engine Coolant Temperature Sensor Circuit High Input: Description
WARNING: This page is about a different car, the 2002 Nissan Xterra and 2002 Nissan Frontier. However, it is still accessible from the selected car via links, so may be relevant.
The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.