Smoke external pre alarm in rear M2 car.Staff(KTB) checked and feedback no abnormality. Rear T213 l ine clear and feedback no abnormality. ~~~~~ T211 3603 (N) Smoke external pre alarm in rear M2 car. Staff(KTB) checked and feedback no abnormality. Rear T213 line clear and feedback no abnormality. SBW NB. CE:Found Tims 2603-smoke extnal.Reset fault  cleared. No abnormality found  N Check #2603 smoke external no abnormalities FC-721 happen once. Clean smoke sensor and function test ok. Done by: Rizman and Koh. 09/05/2024.