What does the temperature gauge on a car do?

Answer 1

Most vehicles use a temperature sensor and gauge that monitor the engine's coolant temperature. The gauge can either reflect the actual engine temperature (with a needle or a digital reading), or it could display a generalized temperature that informs the operator when the engine is at operating temperature or is dangerously hot.

Many older vehicles (made before 1980) also used an engine block temperature sensor. The block sensor was usually impeded in the block and connected a warning light that illuminated when temperatures exceeded a certain amount. Most passenger vehicles did not use a gauge with this type of sensor.

Some vehicles, especially those used for commercial and industrial purposes, use an oil temperature sensor. It works very much the same as a coolant sensor and can be placed in the engine, transmission, or both depending on the need. It would be more common for a warning light to be connected to this type of sensor, but there are aftermarket gauges that reflect accurate oil temperature readings.