Method and system for diagnosing mechanical, electromechanical or fluidic components

There is described a diagnosis method and a system including a structure-born noise sensor which transmits, in a bandpass filtered manner, a measuring signal based on the mechanical resonance frequency and capacity thereof and on an inductance and an evaluating device in which the frequency, at which the measuring signal level exceeds a predetermined threshold value, is defined and which is used for producing an error signal, when the frequency exceeds a second predetermined threshold value. As far as the diagnosis performance requires a small number of electronic components and a low power supply, the diagnostic is integrated into existing devices, in particular into process instrumentation field devices for which a restricted quantity of operating power is available. The method and the system are used for identifying a valve leakage with the aid of an electro-pneumatic positional regulator.