The temp sending unit may be shorted to ground. Unplug the sending unit to see if the gauge drops to cold. If it does, you have a faulty temp sending unit.
Which sending unit? Oil pressure sending unit? Engine temp sending unit? Fuel gauge sending unit?
The temp sending unit should be found close to the thermostat housing. It will have a single wire attached to it.
If the wiring and connections at the coolant temp sending unit check okay start with replacing the coolant temp sending unit. Temp sending unit should be less than $20.
The 4.2 or the 5.3 engine?
The 2.2L or the 4.3L engine?
The 95 Lumina with a 3.1 engine does not have a temperature sending unit. Instead, the dash temp gauge is controlled by the engine coolant temp sensor. This sensor is located on the driver's side, top of the engine.
Need to know which sending unit, there are several, oil, temp, fuel,
THE temp sending unit 4 the inside gauge usally has 1 wire & the sending unit 4 the Computer has 2 wires.
The temp sending unit or gauge is bad, probably the sending unit.
it sends the engine temp to the computer tells if it is hot or cold ....
The sending unit for the computer is on the drivers side right behind the distributor. The sending unit for the gauge in the cab is on the passenger side (both tap directly into the intake