As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIREX FAIL CAUTION MESSAGE ILLUMINATED IN FLIGHT. REMOVED FROM SERVICE. PLACED ON MEL 26-22-00. RETURNED TO SERVICE. MEL CLEARED 3/21/23 BY REPLACING APU FIRE EXTINGUISHING BOTTLE REF. E175 AMM TASK 26-22-01-000/400-801-A. OPS CHECK GOOD. RETURNED TO SERVICE.