TC reported Smoke external alarm at rearM2 car. Rear Train T404 did a line clear and reported no ab normalities observed. Staff(SOM) checked the train and confi rmed no signs smoke or heat on exterior or interior of train ~~~~~ TC reported Smoke external alarm at rear     #2671 Water ingress to fire external unit.Replace unit and function check ok. Not: 2455934 Raise. Done by Koh/Sanip/Rizman. 24/01/23