So I started my 99 XJ this morning, after a decent rain yesterday, and about 25F this morning when I left, and the oil pressure gauge was pegged at 80psi. I first think well crap a wire/ plug broke, but then I notice the pressure drops to about 55-60 psi at idle, so now I am thinking this makes no sense. So then when I shut it off I turn the key back on, and the needle jumps straight to 40 psi with the jeep off. Normally its at 0 psi with the jeep off. So some how it seems the entire gauge has been shifted about 40psi, but why, and where is the failure? Something mechanical? I really don't think so, there is no noise, smoke, smell, leaks, or anything. Something in the sender unit? I think probably the most likely, but I am not sure. Something in the gauge itself? I really don't think so, but maybe. What are your thoughts? Hopefully I can poke around under the hood tomorrow.

Sean