Auto‑monitoring (also called self‑test) is a safety feature built into modern GFCI devices that automatically tests the internal protection circuitry on a regular basis—without requiring the user to press the TEST button.
The GFCI has internal parts that automatically conduct a test on regular intervals to ensure that the GFCI sensing and trip capabilities are intact. If the self-test sequence determines there is a potential loss of protection the GFCI will need to take specific actions such as tripping or providing an indication to alert end users.