TC reported 'Smoke External' present atrear DT car. Staff(EUN) checked and feedback no signs of smo ke or heat on interior and exterior of train. Rear T146 perf ormed line clear in ATPM and confirmed there were no abnorma ~~~~~ 3518 SMOKE EXTER L ALARM.CHECKED CONFIRM FAULT AT TIMS FOUND SMOKR DETECTOR UNIT WITH WATER INGRESS.REPLACED WITH SPARE.FUNCTION CHECKED OK.AKHBAR/AZHAR 25.01.2023 S/N NEW SD-013     OLD   NOTIFICATION  2455947