Method for detecting faults in a device comprising the steps of receiving a plurality of performance parameters, applying the plurality of performance parameters to a first model to produce a plurality of estimated performance parameters, applying the plurality of performance parameters to a second model to produce a plurality of estimated device parameters, computing a plurality of residuals from the plurality of estimated device parameters, computing a plurality of distance measuring from the plurality of residuals, detecting at least one parameter deviation using the plurality of residuals and the plurality of estimated performance parameters, and setting at least one detection flag if the detected at least one parameter deviation is persistent.