As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PRESTART CHECK, FIRE LIGHT WAS ILLUMINATED. PRESTART CHECKLIST WAS ABORTED AND MX WAS CALLED. MX TROUBLESHOT THE SWITCH AND FOUND NO DISCREPANCIES. THEY THEN REPLACED ALL 3 FIRE DETECTORS. THE FIRE LIGHT WENT OUT. NO FURTHER ISSUES OR DISCREPANCIES WERE NOTED.