What does a blue car temperature gauge mean?

[TravisRose]

A blue car temperature gauge indicates that the engine coolant temperature is low. Generally, mechanical temperature gauges are used in vehicles. When the needle points to the blue zone, it means the engine coolant temperature is low; when it points to the red zone, it indicates the temperature is too high. The normal operating temperature for a car engine is around 90 degrees Celsius. The coolant temperature sensor is installed in the engine block or cylinder head's water jacket, directly contacting the coolant to measure its temperature. The temperature sensor used in the coolant temperature gauge is a negative temperature coefficient (NTC) thermistor, whose resistance decreases as temperature rises. It is connected to the electronic control unit (ECU) via a wire.