As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 4245, CREW REPORTED A LAVATORY SMOKE WARNING EVEN THOUGH THERE WAS NO EVIDENCE OF SMOKE IN THE LAVATORY. MX R & R DAU NR 2, RAN BOTH ENGINES AT FULL POWER AND PACKS ON WITH NO INDICATION OF LAVATORY SMOKE ON EICAS AND OPS CHECKED SUCCESSFUL. ACFT WAS APPROVED FOR RETURN TO SERVICE.