My oil pressure started reading a bit high then as rpm increased the oil pressure spiked from the usual 40psi to almost 80, then at idle would creep back down to 50 or so. Oil and engine seemed fine.
A quick test to see if it's the sender. Turn on the vehicle but do not start the engine. The oil pressure should be at 0. Then when the engine is turned on it should steadily climb to about 40psi and hold. Increasing the rpm should result in only a slight increase in oil pressure. When I did this it shot to 40psi with engine still off! So almost assuredly it's a bad sensor/sender.
This is on a 2002 4.0l inline 6. The sender is located on the passenger side of the engine block and very far back towards the passengers feet part of the tub.
First picture shows where it is.
Tools I needed, a small flat head screwdriver. 1/4 inch so width. A 1 and 1/16th inch deep well socket. and a Flex head 1/2 socket ratchet driver. Picture 2.
Picture 3 is what the sender looks like new. $42 from autozone.
There is a small red tab that locks the wired plug into the socket of the sender. It has a blade side and a side with a tab. You push on the tab away from body pulling it completely loose. And try not to lose you'll need it. The connector should just slide right off. Check that the new one fits the connector. Pic 4 and 5
The use the socket and wrench to back out the sender from the block. It's a bit tricky but I found by doing it from underneath it was easy to get a decent amount of turn in with the handle to get it out. It's also a bit tricky to get the wrench on as part of the "tub" of the jeep is in the way. Mine lost no oil when it came out others have complained of a little drip. so be ready just in case.
Then install the new one. Mine Came with a sealant already on the threads so I didn't bother with any. It screwed in smoothly. I don't have nor could find any guideline on torque for it. It seems to bottom out before the base of the sender (brass part) touched up against the knub sticking out from the block.
install the wired connector on the new sender and reinsert the small red tab.
Turned on the jeep but not the engine.. ZERO pressure, turn on the engine psi slowly climbs up to 42 or...holds there, run up engine..never gets above 50.
Checked for leaks..no leaks, drove around the neighborhood. no excessive pressure..home checked for leaks..alls good. I'd say that's a fixed issue. YAY If had to do this again I could knock it out in 15-20 minutes. HOpe this helps anybody else.