TCreported 'B' side cab door kept open by itself. TC isolated 'B's side cab door but train unable todepart due to obstruction motion. ~~~~~ L3 3613 B/S cab door magnetic sensor s/w position re-aligned. Function test 20x - OK. The gap between the sensor s/w is 6mm & vertical is 7mm.  Goh AT. 01/12/2020.