As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAULT LIGHT ILLUMINATED DURING APU START. GROUNDED - YES. WHILE DOING AN EXISTING FAULT CHECK OF THE APU IN REF TO B737-9 AMM 46-13-02. FOUND NO CURRENT OR EXISTING FAULT HISTORY FOR THE APU. ALSO COMPLETED THE BITE CHECK FOR APU IN REF TO AMM 49-61-00. DID THE OPERATIONAL CHECK OF THE APU TWO TIMES RUNNING CONCURRENT AND FOR FIVE MINUTES EACH AND NO FAULT OCCURRED.