As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FA'S REPORT ABNORMAL NOISE COMING FROM AFT (GALLEY) AREA OF AIRCRAFT . GROUNDED - YES. REVIEWED HISTORY. ACCOMPLISHED FIM 49-55-808 NO CURRENT FAULTS. MAX APU EGT DURING MES WAS 475 DEGREES. NO OTHER DEFECTS NOTED. ACCOMPLISHED FIM 36-10-806. NO FAULTS WITH INITIAL EVAL. ISOLATION VALVE OPS CK GOOD. REMOVED AND REPLACED ECU REF B737-900 AMM 49-61-12/401. OPS CHECK GOOD. ACCOMPLISHED FIM 49-55-808 AND FIM 36-10-806. NO FAULTS.