As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TROUBLE SHOOTING FOUND ACTIVE/CURRENT FAULT 49-41250 START CONVERTER UNIT SHOWS SYSTEM INOP ON APU. GROUNDED - YES. ACCOMPLISHED B737-800 FIM 49-40 TASK 811. INITIAL EVALUATION SHOWS NO CURRENT STATUS MESSAGE. APU START AND OPERATION IS NORMAL. PERFORMED ENGINE START WITH NO APU FAULTS. RE-ACCOMPLISHED BITE WITH NO CURRENT FAULTS FOUND. REMOVED AND REPLACED APU STARTER GEN IAW B737-800 AMM 49-11-21. GROUND VERIFICATION C/W.