Where is the temperature sending unit for a 99 cavalier 2.2

Hello, a sending unit is typically something I would consider if the gauge is all the way low or all the way high. Fluctuation, unless seriously erratic, is likely caused by real changes in engine coolant temperature. The gauge sensor is located on a coolant line at the top of the engine, nearest the side with the belt and pulleys. Testing can be performed there. A diagnostic tool can be used to see what the temperature sensor is reading. which is usually a very good way to find out if a problem is occurring.