DTC P0116: Engine Coolant Temperature Sensor Circuit Performance: Description

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. When the engine coolant temperatures are low, the resistance of the sensor is high. When the engine coolant temperatures are high, the resistance of the sensor is low. The ECT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground tot he ECT low reference circuit. The ECM uses the following sensor inputs to calculate a predicted engine coolant temperature:

• The ECT sensor.
• The intake air temperature (IAT).
• The mass air flow (MAF) sensor.
• The engine speed (RPM).

The ECM compares the actual engine coolant temperature to a predicted engine coolant temperature. If the ECM detects that the actual engine coolant temperature is more than the predicted engine coolant temperature, DTC P0116 sets.