TC reported Internal Smoke Alarm at front M1 car. Staff(EUN) checked and feedback no sign of smoke o r heat found in train. ~~~~~ Fault unable to  duplicate In depot. 1557 checked - no internal smoke alarm.    Cleaned smoke sensor on No.1 and no.2 end. Checked fire panel - no water ingress. Further monitored - no anomalies or fault recurrence. N.A/fairuz/faizal/azli/27.07.22