What does the thermostat do in my car? The car thermostat is an important part of the car engine cooling system. It helps to regulate the temperature of the car engine coolant. The car thermostat is usually located near the car engine, and it consists of a small sensor that measures the car engine temperature. When the car engine coolant temperature gets too high, the car thermostat opens and allows the coolant to flow into the car engine. This helps to cool down the car engine and prevent it from overheating. The car thermostat also helps to regulate the flow of coolant through the car radiator. When the car radiator is not getting enough coolant, it can cause the car engine to overheat. The car thermostat helps to prevent this by regulating the flow of coolant through the car radiator.