As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKE OFF RECEIVED SMOKE TOILET MSG WITH NO ABNORMAL ODORS OR ACTUAL SMOKE. QRH FOLLOWED AND RETURNED TO BASE WITH UNEVENTFUL LANDING. MX INSPECTED ACFT WITH NO DEFECTS FOUND, MSG RESULTED FROM RESIDUAL DE-ICE FLUID ENTERING THE ECS SYSTEM. GROUND RUNS PERFORMED WITH DEFECTS NOTED.