As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE TO EWR, WITH SUPPLEMENTAL HEAT ON, A BURNING ODOR WAS REPORTED IN THE COCKPIT. THE ODOR DISSIPATED WHEN THE HEAT WAS TURNED OFF. COULD NOT DUPLICATE. THE SUPPLEMENTAL HEAT WAS OPERATED FOR SEVERAL MINUTES ON THE GROUND AND NO ODOR WAS NOTED. HEATER OPS CHECKED GOOD.