Abstract: Detection filter,which is actually a specific class of observers,can fix the output error direction of the system,so that it can be associated with a particular failure mode and its known design failure direction.The detection filter algorithm developed by White & Speyer is applied to a sensor fault detection and isolation system in an aeroengine control system.A nonlinear engine computer simulation model is set up and used to process the close loop simulation which includes sensor fault detection and isolation system.An isolation method is presented to isolate the fault sensor location.The results of the simulation show that the present fault detection and isolation system is very effective.