Abstract: Techniques for detecting localized changes in a distributed service based on aggregate device signals. Certain implementations may leverage a plurality of networked nodal devices to serve as an ad-hoc sensor network for detecting changes in a service provided to the nodal devices. For example, status changes at each nodal device indicative of a disruption in a service provided to the nodal device may be reported and utilized to diagnose regional or localized disruptions in a common service received by a large group of devices. In some implementations, the service provided to the nodal devices may be a distributed service, for example, electric power or Internet access. The device signals may include reports from or based on status changes of mobile devices or other network-enabled electronic devices, such as changes in battery-charging status or network-connectivity of the respective mobile device.