Abstract: A thermostat monitoring method includes measuring an engine coolant temperature with an engine coolant temperature sensor a predetermined amount of time after engine startup, comparing, with a controller, the engine coolant temperature to determine whether the engine coolant temperature has met a predetermined threshold, when the engine coolant temperature has met the predetermined threshold, measuring a plurality of engine coolant temperatures with the engine coolant temperature sensor, comparing with the controller each of the plurality of engine coolant temperatures with a corresponding predetermined temperature model, and increasing a passing index with the controller for each of the plurality of engine coolant temperatures that is greater than the corresponding predetermined temperature model or reducing the passing index for each of the plurality of engine coolant temperatures that is less than the corresponding predetermined temperature model.

Abstract: A thermostat monitoring method includes measuring an engine coolant temperature with an engine coolant temperature sensor a predetermined amount of time after engine startup, determining with a controller one of four zones to determine whether a thermostat will pass or fail, based on the one of four zones determined, accumulate with the controller one a pass index or a failing index, when the pass index reaches a first threshold, reporting a pass with the controller, and when the failing index reaches a second threshold, reporting a fail with the controller.

Abstract: A thermostat monitoring method includes measuring an engine coolant temperature with an engine coolant temperature sensor a predetermined amount of time after engine startup, comparing, with a controller, the engine coolant temperature to determine whether the engine coolant temperature has met a predetermined threshold, when the engine coolant temperature has met the predetermined threshold, measuring a plurality of engine coolant temperatures with the engine coolant temperature sensor, comparing with the controller each of the plurality of engine coolant temperatures with a corresponding predetermined temperature model, and increasing a passing index with the controller for each of the plurality of engine coolant temperatures that is greater than the corresponding predetermined temperature model or reducing the passing index for each of the plurality of engine coolant temperatures that is less than the corresponding predetermined temperature model.