As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE MAGNETIC PLUG WARNING LIGHT CAME ON DURING FLIGHT. PILOT LANDED AIRCRAFT AND MAINTENANCE WAS NOTIFIED. MECHANIC INSPECTED MAGNETIC PLUGS AND FOUND PASTE ON UPPER ENGINE GEARBOX MAGNETIC CHIP PLUG. MECHANIC CLEANED AND REINSTALLED PLUG PERFORMED MAINTENANCE IAW MM.