High oil pressure will cause oil not to be contained at the weakest point in the lubrication system.
That could be a seal, a gasket, the oil cooler, a sensor or anywhere else.
A simple analogy:
Fill a bicycle pump with water, put your finger over the end and push the plunger. Without too much effort the pressure created will overcome your finger's ability to contain it and presto: a leak!
Now consider the same pump with several different holes in it and several different people with their fingers covering the holes. Whoever allows the fluid out first is the weakest!
If the sensor is an electronic one, a simple test is to power up the instruments without starting the engine. If your oil pressure goes up you have an instrument/sensor problem. If it only goes up once you start the engine then you probably have a stuck PRV .