Which of the following often indicates a fault in a smoke detector?

A triggered alarm with no smoke is a clear indication of a fault in a smoke detector. This situation often suggests that the detector may be malfunctioning, possibly due to internal errors or issues with the sensor itself. A properly functioning smoke detector should only activate when it detects smoke particles in the air. When an alarm is triggered without the presence of smoke, it raises concerns about the effectiveness of the detector to accurately sense smoke in actual fire situations.

In contrast, continuous blinking of the LED indicator may indicate that the unit is in a standby mode, functioning properly but requiring occasional maintenance checks. Silence during tests typically signifies that the detector is working as intended, given that it may not activate if no smoke or heat is present. Slight battery drainage is a normal aspect of smoke detector operation, particularly in battery-operated models, and does not inherently signal a fault unless it leads to a complete power loss.