As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER APU START APU "MAINT" LIGHT ILLUMINATED. CHECKED OIL LEVEL SENSOR CONNECTOR P16 AND CONNECTOR P3 BOTH ARE GOOD. CLEANED CONNECTOR. REPLACED APU ELECTRONIC CONTROL UNIT REF AMM 49 61 12. COMPLETED FIM TASK 49 90 00 810 804. PERFORMED OPS CHECK NO DEFECTS NOTED.