TC reported TIMS showed obstacle detected at car 3656 'B1' door. Fault self-cleared and did not recu r at subsequent stations. Staff(DBG) checked and confirmed c ar 3656 'B1' door opened and closed normally. TC reported TI ~~~~~ TC reported TIMS showed obstacle detecte     Checked Tims no FC.Staff checked #3656-B1 door at DBG. Checked ER 6 stations before DBG & 4 stations after,no abnormalities,DIR ok.Checked door operation ok,open/close speed pass.FOD not found,door cycle test ok.No rubbing marks.Push/pull force within criteria.Door mating gap 64.2mm ok.Door lock s/w red line ok,cushion rubber ok.DCS distance to actuactor plate ok.No door wobble,service J-rail & guide rail ok.Postulate FOD dislodged while door closing. Checked by Luke. 23/03/23