As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOTS REPORTED OIL PRESSURE DROPPED AS LOW AS 10 PSI IN THE CIRCUIT. MAINTENANCE FOUND GAUGE TO BE READING 15 TO 20 PSI LOWER THAN A CALIBRATED SHOP GAUGE. THE GAUGE AND THE SENDER WERE REPLACED WITH A NEW SET AND THE ACFT WAS RUN WITH NO FURTHER FAULTS.