To locate the oil pressure sensor in a truck, first locate the oil filter, and look in the immediate vicinity for a small metal cylinder connected to an electrical wire. On most trucks, the oil pressure sensor is near the oil filter, as the two parts often require replacement at the same time. However, if your truck's oil pressure sensor is not near the oil filter, contact the vehicle's manufacturer or a service station for advice.
If you need to remove or replace the oil pressure sensor, disconnect the truck's battery before you begin. With the battery disconnected, unplug the electrical cable connected to the oil pressure sensor. Most oil pressure sensors have a protective rubber boot that requires removal before you can access the sensor itself. Using a screwdriver or your fingernail, carefully peel back the rubber boot until you can see a small latch that holds the connector to the pressure sensor. Hold down the latch to detach the connector, and remove the sensor by unscrewing it.
Removing the oil pressure sensor may cause a small amount of oil to leak out of the housing; clean this up using a rag. Screw the new oil pressure sensor into place, snap the connector latch back into place, and put the protective boot on the new sensor. Reconnect the electrical cable and battery, and check for leaks after running the engine for a few minutes.