As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF, THE CREW RECEIVED A (SMOKE TOILET) CAUTION MESSAGE WITH THE LAVATORY SMOKE DETECTOR PREVIOUSLY DEFERRED. THE AIRCRAFT RETURNED TO DEPARTURE, WHERE IT LANDED SAFELY. MAINTENANCE CLEANED OIL FROM BOTH PACKS AND REMOVED AND REPLACED THE COALESCER BAG. OPERATIONAL CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (K)