TC reported Fire External Alarm and TIMSshowed car 3544 smoke external alarm. Rear T442 feedback no abnormalities observed. Staff (BBT) checked the train and f eedback no signs of heat nor smoke in train. ~~~~~ Isolated 3544 ext smoke detector via SDR11. Ops 20 for ext smoke detector check and c/o if necessary Luke, Zul BSDRSD. To check ext smoke detector and replace if necessary.     Replaced the above mention done. Security check and function test ok. Reinstall done. Not: 2466643 Raised to CSC. Done by Saini/Haslan. 02/03/23.