What was found
FLIGHT 2346. CLIMBING THRU APPROX 23,000 FT, MASTER WARNING LAV SMOKE CAME ON, RAN CHECK LIST, CONFERRED WITH FLIGHT ATTENDENTS, DETERMINED PAX IN FORWARD LAV. REMOVED FROM SERVICE. INSPECTED FWD LAV, NO OBVIOUS DEFECTS. TESTED SMOKE DETECTORS REF E175 AMM 26-14-01-700-801-A STEP 6 PARA. B. ALL CHECKES GOOD. RETURNED TO SERVICE. NO PARTS REPLACED.