As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE TOILET CAUTION MESSAGE APPEARED AFTER TRANSFERRING BLEEDS TO APU DURING APPROACH. AFTER TURNING OFF PACKS, MESSAGE CLEARED. AIRCRAFT HAD BEEN DEICED PRIOR TO DEPARTURE. (FLT 7430) PERFORMED OPERATIONAL CHECK OF AIR CONDITIONING SYSTEM USING BOTH APU AND ENGINE BLEEDS AS A SOURCE. COULD NOT DUPLICATE SMOKE IN CABIN. POSSIBLY GLYCOL INGESTED DURING DEICING. OPERATIONAL CHECK GOOD.