TC reported intermittent BCU fault at car 3641. ERS-12 ~~~~~ #3641 ER download PTU006 FC: 309 BCU brake demand PWM fault. ER show brake at 3641 stuck when at coast. Unable to duplicate. Brake cyclic test with 750 and without 750. Check ACU no sign of air leak or hunting. BCP within criteria. STBS both cab not operated. Brake cyclic test done at both cab. Replace BCU. WDC setting, brake cyclic test ok. BCP within criteria. Limited movement ok. Not: 2248280. BCU-New s/n: 1544-290.  Old s/n:  1446-069. Done by Saini/Haslan/Henry. 13/02/21. Depot found 3641 BCU intermittently faulty and did not release brakes when commanded. Replaced BCU. Brake functional check -ok.