Ok, so today I went and did some wheelin around some local trails. Nothing too crazy, but when I got home I cleaned off the whole jeep at the local car wash. I like to clean it after wheelin so nothing freezes caked up with mud and causes any complications. The oils pressure was fine until I got home and let it sit a bit, then when I went out to swap vehicles in the drive the oil pressure went all the way up to 80 and stuck. I don't know if cleaning the jeep froze something or if I have another issue. Any help is appreciated. It is a 99 jeep cherokee 4.0.

 

Not sure about on the Jeep, but chevy LS oil pressure sensors fail at max PSI, and often. Possibly the sensor just failed.

 

Dead sensor or a bad wire.

 

if it happened after you washed the jeep, the plug probably got wet and lost contact with the sensor. Get some electrical parts cleaner and some die electric grease and see if that gets it back.