I agree regarding the indicators being possibly duff.
I had this issue for a year or two after I got my plane from new. The oil pressure indicator uses a transducer which has a vent hole and it gets moisture in there which corrodes the resistor bridge.
Socata released an SB for it, which mistakenly asks for the connector to be sleeved, so they never sussed that there is a hole in the side of the connector base
Incidentally, what exactly is the problem if the oil pressure is too high? Could it crack the crankcase if it was say 1.5x too high? That would suprise me. What could happen is that an "excessive" oil pressure could cause more engine heat to be absorbed by the oil, which would reduce the CHTs but would need a bigger oil cooler to maintain the oil temp to a reasonable level.