An apparatus for monitoring a signal path is provided. The signal path includes a first processing unit, which generates a first signal based on an input signal of the signal path, and a second processing unit, which generates an output signal of the signal path, wherein the output signal depends on the first signal. The apparatus includes an output estimation module configured to determine an estimated output signal of the second processing unit based on the input signal. Further, the apparatus includes a comparison module configured to determine a state of the signal path based on a deviation of the output signal from the estimated output signal.