As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOT RETURNED AND REPORTED THAT OIL PRESSURE WOULD NOT GO INTO THE GREEN OPERATING ARC AT 1700 AND WAS LOW AT IDLE. MAINTENANCE INSTALLED A SHOP MASTER GAUGE AND FOUND THAT THE ACFT GAUGE WAS READING 10-15 PSI LOWER THAN THE MASTER GAUGE. A NEW GAUGE WAS INSTALLED AND CHECKED. IT WAS FOUND TO BE ACCURATE.