TC reported TIMS showed obstacle detected at Rear M1 car 'B4' Door when train doors opened at statio n platform. Fault clears when train departing and only appea rs when train doors opened at station. Staff (SOM) checked t ~~~~~ 1629 TC reported TIMS showed obstacle detected at 'B4' door when train doors opened at station platform. Fault clears when train departing and only appears when train doors opened at station. Staff (SOM) checked the train and feedback door did not opened. Staff feedback could not board the train due to train crowded. Staff (RFP) confirmed Rear M1 car 'B4' door did not opened. Door was subsequently isolated in closed position with assistance from staff (MSP) with door isolated sticker pasted.  1629 B4 door performed the following checks : Check fault code: NIL FOD found: N Weather strip condition ok: Y Checked roller condition ok: N, 1629 B4 RHS outer roller delam Clean J-rail & guide rail: Y Push/pull door smooth & no wobble: Y, after rectification Door cyclic test 20x, DIR extinguish ok: Y, after rectification TIMS door static timing test pass: Y, after rectification Door lock switch red line flush with surface for positive latching: Y Door close switch actuating plate distance ok: Y    Door gap (criteria 63mm+1.5mm): 63.7mm Replaced all #1629 B4 rollers with iron rollers. Security/function check - OK.  Kamarul/Alan/Sugu/Lee PT 45312