TC reported front DT car A2 door not proven closed. TC unable to open train doors in AM and ATPM. TCperformed platform duty. TC open and close once - fault cle ared. Staff (BBT) feedback there was no abnomalities. Fault ~~~~~ 3627 ER showed "DOOR OBSTACLE FAULT' (DOBS) on A4 door. Door resistance 70N - OK, smooth & no rubbing sound. Checked motor current registered - OK. Checked no loose connections to DCP. Door open/close timing within criteria. Cleaned J-rail & door guide rail as preventive measure. Door cyclic test 20x - OK.  Selvan/Lee PT. 04/05/2020.