As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 4137 YHZ-EWR CREW REPORTED LAV SMOKE ON CLIMBOUT. SMOKE IN CABIN. A/C RETURNED TO YHZ AND LANDED SAFELY. CONTRACT MX PERFORMED ABNORMAL SMELL INSPECTION WITH NO DEFECTS NOTED. RAN ENGINE WITH CREW COULD NOT DUPLICATE FAULT. A/C OK FOR SERVICE.