As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE PILOT REPORTED LOW EGT ON THE LEFT ENGINE. A VISUAL INSPECTION OF NR 6 CYLINDER WHERE THE EGT PROBE IS LOCATED REVEALED A CRACK AT THE LOWER SPARK PLUG HOLE. AFTER REMOVING THE CYLINDER, FOUND THE CRACK WENT FROM SPARK PLUG HOLE TO SPARK PLUG HOLE WITH MISSING METAL AROUND THE EXHAUST VALVE.