TC reported smoke external at rear M2 car. Rear T231 conduct a line clear and confirmed no abnormali ties. Staff(SBW) checked and confirmed there was no heat andsmoke. ~~~~~ To check ext smoke detector #2506-Replaced ext smoke detector and function check no abnormalities. Not: 2472385 raise. Done by Samsudin/Fazil. 20/03/23 TC reported smoke external at rear M2 car Checked smoke external FC only at 2506. Isolated 2506 ext smoke detector by removing SDR11. Ops 20 to check external smoke detector. Luke BSDRSD 45005