Train doors at FDT car 'B1' side were not proven closed. TC recycled train doors once - ok. Fault di d not recur at subsequent stations. ERS-10 ~~~~~ Train doors at FDT car 'B1' side were no     Check door operation-1)Door cyclic test-satis,2)door speed-satis,3)FOD-not found,4)Door close s/w(14.5-15mm)within criteria-satis,5)Door plunger red line -satis.6)Door mating strip not within criteria(65mm)Swapped #3623 B1 DCU(S/N:1503W020011S009) to B2 DCU (s/n:1503w020d115043)Door mating strip adjusted to 63.7mm.To monitor further in M/L.(Fault code 933 saloon door B1 close operation time out)Checked fault trace and found door gap to be 15.2cm during the time of which fault occured. Done by Ashwin  21/11/22