As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT SMOKE TOILET MESSAGE ILLUMINATED, COMPLIED WITH QRH RETURNED TO DEPARTURE, SMOKE MESSAGE EXTINGUISHED AFTER COMPLETION OF QRH CHECK. REMOVED AND REPLACED APU ASSY ON WO 137202, RAN ENGINES AND PACKS TWICE ON GROUND, NO SMOKE NOTED. (K)