Malfunction Threshold

Malfunction determination 1:

If the difference between the current measured coolant temperature at the radiator (ECT 2) and the initial coolant temperature at the radiator (ECT 2) is at least 13°F (7°C) when the estimated coolant temperature at the engine (ECT 1) reaches 164°F (73°C), a malfunction is detected (thermostat stuck open); or if the coolant temperature at the radiator (ECT 2) only reaches 68°F (20°C), a malfunction is detected (thermostat malfunction).

Malfunction determination 2:

When the calculated engine coolant temperature (ECT 1) reaches 158°F (70°C) before the measured engine coolant temperature (ECT 1) reaches 158°F (70°C), a malfunction is detected.