As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING APPROACH, PILOT HAD AN ENGINE FIRE INDICATION ON THE CAUTION PANEL. PERFORMED A NORMAL LANDING AND TAKEN OUT OF SERVICE. REPLACED ASU1 CARD, CHECKED WIRING IAW WIRING MANUAL, AND PERFORMED CHECK FLIGHT. COULD NOT DUPLICATE ISSUE, RETURNED TO SERVICE.