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 enabling criteria for diagnostics. The PCM will record the
amount of time the engine is OFF. At restart the PCM will compare the
temperature difference between the ECT and intake air temperature
(IAT). If the temperature difference is not within the calculated amount,
after the predetermined soak time, this DTC will set.
WARNING LIGHTS