As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, AFT LAVATORY WARNING LIGHT CAME ON AND ENTIRE CREW COULD DETECT SMOKE. PERFORMED CHECKLIST AND RETURNED TO DEPARTURE. FOUND ODOR TO BE COMPRESSOR WASH SOLUTION. PERFORMED PACK RUN IAW AMM 21-00 AND ENGINE RUNS IAW 71-00.