DTC P0116: ECT Sensor Circuit Performance: Description

The Engine Coolant Temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The Powertrain Control Module (PCM) supplies 5 volts to the signal circuit. When coolant temperatures are low, resistance is high. When coolant temperatures are high, the resistance is low. The PCM uses this input for engine controls and the enabling criteria for the diagnostics. The PCM will record the amount of time that the engine is off. At restart, the PCM will compare the temperature difference between the ECT and the Intake Air Temperature (IAT). If the temperature difference is not within the calculated amount after the predetermined soak time, this DTC will set. Before failing this test, the PCM will inspect for the presence of a block heater.