There are several sending units, engine temp, oil pressure, fuel level to name a few. We need to know which one and also the year, make and model vehicle.
Remove tank, remove sending unit, replace pump, replace tank.
you have to remove the fuel pump it is connected to it, it has to be replace as one unit
Refer to repair manual for proper instructions Remove gas tank remove sending unit replace with new sending unit and properly reinstall sending unit and gas tank
Remove the gasoline from the gasoline tank. Remove the fuel line from the gasoline tank. Remove the fuel sending unit retaining plate. Reverse the process to install the new fuel sending unit.
Lower the Gas tank. Remove the sending unit/fuel pump from the tank and replace the unit. The sending unit and fuel pump come together.
You will have to replace the fuel module which consists of the pump, sending unit and sock filter. Which means you will have to remove the fuel tank.
you have to remove rear seat ,under the seat there's two covers , one is for the fuel pump , the other is for the fuel gauge sending unit .Remove cover on passenger side and remove fuel gauge sending unit .
Remove oil sending unit and replace with a mechanical gauge
If you suspect the sending unit may be faulty just replace it with a new one, they are not expensive but a little difficult to remove and replace.
you have to remove the oil pan and replace the pump
Remove the oil pressure sending unit retaining ring. Remove the wiring harness from the sending unit. Poll the sending unit out of the engine.
Remove the fuel sending unit from the fuel tank (the process to do this depends on what your vehicle is), unplug it from the weatherpack connector, install the new unit, plug it back in.