The classic Jeep Cherokee XJ was built from 1984 through 2001 and is a favorite among many Jeep enthusiasts. Though it is known for its durability and long lifespan, it was not without its faults. Among these is the notoriously unreliable oil pressure sending unit.
The oil pressure sending unit -- the sensor -- used on 1984-2001 Jeep Cherokee models commonly fails. Usually, the result is a continually high reading, "pegged out" at 80 psi or more.
The simplest way to determine if a faulty sensor is causing high oil pressure readings is to replace the sensor. The job is not too difficult for the amateur home mechanic.
If you aren't comfortable replacing the oil pressure sensor yourself, or if you have done so and still get abnormally high pressure readings, have the vehicle's oil system checked professionally.