As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A/C REPOSITION APU FAILED TO START. GROUNDED - YES. ACCOMPLISHED B737-900 FIM 49-40 TASK 804 NS VERIFIED APU FAULT ON CDU. REMOVED AND REPLACED APU IGNITION UNIT REF B737-900 AMM 49-41-31-000-801/400-801. ACCOMPLISHED BITE TEST AND NO FAULTS FOUND. APU STARTS AND OPERATES NORMAL.