A sensor system for detecting a leak of a system component from an electrochemical storage system, in particular a lithium-ion battery. To determine a defect in the electrochemical storage system, the sensor system includes a reaction chamber containing a detection component, and a measuring device for determining a physical variable within the reaction chamber. The value of the physical variable is changeable by a chemical reaction of the system component with the detection component, so that a leak of the system component is detectable via a change in the value of the physical variable. Also described is a sensor element for such a sensor system, an electrochemical storage system having such a sensor system or sensor element, the use of such a sensor system or sensor element, and a mobile or stationary system, for example an electric vehicle, equipped with the sensor system, the sensor element, or the storage system.