As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW RECIEVED A BTMS OVT MASTER WARNING DURING TAKE OFF FROM IAD. THE CREW RAN THE QRH BUT THE INDICATION KEPT COMING BACK. THEY DECLARED AN EMERGENCY AND RETURNED TO IAD. THE FLIGHT LANDED SAFELY AND TAXIED TO THE GATE. REMOVED AND REPLACED RH OB BRAKE TEMP SENSOR. OPS CHECK GOOD. THIS CLEARS MEL.