As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAULT LIGHT ILLUMINATED ON FIRST START & SECOND ATTEMPTS AFTER FAULT LIGHT EXTINGUISHED. ACFT GROUNDED. FOUND 2 FAULT CODES ON THE APU BITE CHECK. FOUND IGN CIRCUIT OPEN 49-41181 AND FIRE HANDLE PULLED 49-11021. CYCLED FIRE HANDLE AND REPLACED THE APU IGNITER PLUG IAW AMM 49-41-51. NO HELP. REPLACED IGNITION UNIT REF TASK 49-41-31, PERFORMED SEVERAL STARTS NORMAL, OK THIS DATE.