Why does the water temperature warning light disappear after restarting?

[Grady]

The reasons why the water temperature warning light disappears after restarting are: insufficient coolant, thermostat malfunction, radiator fan issues, or water circulation pump failure. When the water temperature warning light comes on, you should pull over to the side of the road, open the engine hood, and allow the engine to cool down. Most engines used in cars are water-cooled engines, which rely on coolant circulating continuously within the engine to remove excess heat. The water temperature warning light is a bimetallic sensor switch screwed into the engine block water jacket. This switch controls the red indicator light on the dashboard. Within the normal operating temperature range, the switch contacts remain open, and the indicator light stays off. When the water temperature exceeds the normal range, the switch arm contacts close, causing the red light to illuminate.