As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE SHUTDOWN AND ENGINE OIL PRESSURE TRANSMITTERS WERE SWAPPED DUE TO UNABLE TO DUPLICATE. AFTER TAKE OFF LEFT AT 6,000 FT, OIL PRESSURE ANNUNCIATOR ILLUMINATED, OIL PRESSURE WENT TO ZERO FOLLOWED BY MASTER CAUTION LIGHT. FOLLOWED ABNORMAL CHECKLIST. LIGHT EXTINGUISHED AND RETURNED AT 10,000 FT.. DIVERTED BACK TO DEPARTURE. LANDING WAS UNEVENTFUL. SWAPPED FOR LEFT ENGINE TO RIGHT ENGINE. MAINTENANCE REPLACED THE LEFT OIL PRESSURE TRANSMITTER. GROUND OPS AND LEAK CHECKS GOOD. AIRCRAFT WAS RETURNED TO SERVICE.