#1 in the picture below points to the electrical connection of the oil pressure sensor.
This picture shows the engine from the back side, as if you are looking from the firewall side. The truck will be okay to drive until repairs are made. The oil pressure is okay, the sensor is just sending a false reading.
As noted below - chances are that the sending unit is defective - OR - the wire to the sending unit is loose or shorted. For these sending units, it will peg one way if shorted and the other way if disconnected (or open / broken wire).
Chances are that you have a defective oil pressure sending unit. Rarely the gauge goes bad.
Remove the wire on the sending unit and see if that changes the reading. If it does, replace the sending unit.
