As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT WITH NO PATIENT ON BOARD, THE FIRE WARNING AUDIO TONE WENT OFF WITHOUT ANY SECONDARY INDICATIONS, LANDED AT CLOSEST SUITABLE LANDING AREA. FOUND ELECTRICAL CONNECTOR TO ONE OF THE FIRE DETECTOR PROBES HAD A PIN CORRODED, REPLACED PIN & OPERATIONS CHECKED WITHOUT ANY FURTHER ISSUES.