If it's a V-8 engine then it will be screewed into the drivers side head all the way up front by the first spark plug. On the V-6 engines it will be in the same head but all the way back towards the last spark plug.
It's a 30 dollar part. The unit should be located near the filter. Unplug/Unscrew the old one and insert new and plug in.
Front of the engine, about half-way down, facing the radiator.
The oil pressure sending unit on my 1997 silverado is on the top of the engine behind the intake manifold. It took a while to find it.I had to climb on top of the engine and look down to the block up near the firewall I was having eratic oil pressure readings and the sending unit was the problem.
the fuel pump is in the fuel tank--which is located about half way back on the drivers side...
inside the gas tank
back side of the engine block about half way up
impala sluggish after second gear
The crankshaft is located inside the lower half of the engine. The engine must be removed and disassembled to gain access to the crankshaft.
It is probably a bad float and you will have to replace the sending unit assembly.
the sending unit is located in the engine block, sends a signal to the temp guage, mind you the engine temp guage is not accuate, but at the 1/2 way mark is "normal" for the engine operating temperature
the main oil press sending unit is located on the drivers side, half way back and bout 6" above the oil pan.there is also a sending unit that is part of the v v a system and is located either on the side of the head or under the valve cover.
On the left side frame rail about half way back, in the channel of the frame