TC reported Smoke External Alarm at front M2 car. Rear T227 feedback no signs of heat nor smoke on t rack. Staff (YCK) checked the train and feedback no signs ofheat nor smoke in train. TC reported Smoke External Alarm a  ~~~~~ TC reported Smoke External Alarm at 2668 car. Rear T227 feedback no signs of heat nor smoke on track. Staff (YCK) checked the train and feedback no signs of heat nor smoke in train. CE: 2668 smoke external reset ok  Found external smoke faulty and very dirty. Changed out and function tested ok. Smoke external Notification: 2558086 Done by: Sanip/Koh/Jack 45296