As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE GROUND TERMINAL OF THE ALTERNATOR WAS CORRODED/DIRTY MAKING BAD CONTACT. THE OIL TEMPERATURE GAUGE WAS "BACK READING" OFF THIS WHICH CAUSED THE GAUGE TO READ HIGH. CESSNA TECH REP WAS ADVISED OF THE PROBLEM AND RECOMMENDED THIS TO CHECK AS A SOLUTION WHICH FIXED THE INDICATION PROBLEM. THE INITIAL PROBLEM WAS THE OIL TEMP GAUGE WENT TO THE RED LINE DURING FLIGHT.