Abstract: A circuit for detecting faults in a magmeter system in which an electrically conductive fluid flows which is maintained at a reference potential. The circuit includes at least two electrodes in contact with the fluid. The electrode signals are conducted to the corresponding inputs of a measuring circuit. An alarm circuit is connected ahead of the measuring circuit. A difference in the magnitude of the values (+U.sub.S and -U.sub.S) of the electrode signals and/or non-symmetries in the noise content of the electrode signals and/or a disturbance in the high frequency signal (U.sub.G) in a loop which contains the electrodes and a high frequency producing generator causes an alarm to be activated.