As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIREX FAIL MESSAGE ON EICAS APPEARED MORE THEN SIX TIMES AND SELF EXTINGUISHED EACH TIME. ALL HAPPENED FIRST 20 MINUTES OF FLIGHT. REMOVED FROM SERVICE. UPON ARRIVAL NO MESSAGE IN EICAS. INTEROGATED CMC AND FOUND FC 26220047UT1. C/W E175 FIM 26-22-00-810-803-A. TRANSITORY PER STEP 6B(1). RAN APU FOR 1 HOUR. COULD NOT DUPLICATE. RETURNED TO SERVICE.