Diagnostic Aids
WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.
After starting a cold engine, the following scan tool parameter value should rise steadily and then stabilize: Radiator Coolant Temperature Sensor - The temperature should stabilize after the component has opened: Engine Coolant Thermostat