As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PROPELLER OVERSPEED INDICATION ENG#1. AIRCRAFT TURN BACK TO AIRPORT AFTER SHUTTING DOWN AFFECTED ENGINE ACCORDING TO PROCEDURE. CORRECTIVE ACTION: SIGNAL CONDITIONER UNITS SWAPPED BETWEEN ENG#1 AND ENG #2. CLEANED OVERSPEED GOVERNOR SOLENOID VALVE CONNECTOR. ENGINES RUNNUP TEST OK.