Diagnostic system including a sensor device with a sensor for generating signals corresponding to a first operational condition, a control device with a timer and function for performance of measurements, and a signal transmission device. The system includes a device for determination of a second operational condition of the system component and configured where the sensor value of the signal transmission device corresponding to the first operational condition is furnished when the sensor value corresponding to a second operational condition of the transmission mechanism is higher or lower than a comparative value, and housing component of a lubricant container and in particular closure device for sealing an opening of such a housing component from a lubricant which is present in the operational use thereof in an internal space thereof, having arranged therein: at least one sensor device comprising at least one sensor for determining the water content in the lubricant.