What feature might alert users to a system malfunction?

Self-testing functionality is the correct feature that can alert users to a system malfunction. This feature enables the alarm system to periodically conduct automated checks on its components, such as sensors, alarms, and communication systems. During these tests, the system verifies that all elements are functioning correctly. If the system detects any issues, such as a sensor failure or a communication error, it can trigger an alert to inform the user or monitoring service of the malfunction.

In terms of the other features: remote access allows users to monitor and control their alarm systems remotely but does not inherently check for malfunctions. Wireless communication is essential for the operation of wireless alarm systems but doesn't directly indicate whether the system components are working as intended. Zone bypassing is a feature that allows certain zones of a security system to be temporarily disabled, typically for maintenance or in situations when a sensor is addressed specifically, but it does not provide alerts about the overall health of the system.