A debris monitoring system has a first sensor configured to generate a first signal indicating a presence of a metallic particle in a lubrication system. A second sensor is configured to generate a second signal indicating the presence of a metallic particle in the lubrication system. A signal processor is configured to determine a presence of a metallic particle in a fluid passage based on a comparison of at least the first signal and the second signal; the second signal being used to verify accuracy of the first signal. A gas turbine engine and a method for monitoring a fluid passage for debris are also disclosed.