I've been having this high pressure reading occasionally but more frequently over the last 2 months (like once a week).

It only happens when I start the XJ. I shut it off and restart it but the high pressure reading is still there. I let it cool down after driving it and next time the oil pressure reading is normal. Have someone have this issue?? Is it problem?? What to check??

 

The oil pressure sending units are notorious for failing. If it will make you feel better, borrow/rent a mechanical gauge and check it first before replacing the sender, which is located right above the oil filter.