This paper considers the fault detection problem for networked switched control systems subject to repeated scalar nonlinearities and stochastic disturbance under an event-triggered scheme. A nonlinear fault detection filter is proposed to generate the residual signal and detect system faults, and an event triggered strategy is applied to limit signal transmission. Sufficient conditions to guarantee an event based residual system is mean-square exponentially stable with the desired performance are obtained using average dwell time stability theory and a positive diagonally dominant Lyapunov functional approach. The corresponding fault detection mechanism parameters are calculated using the linearization technique. The event-triggered fault-detection filter and controller coordinated design are extended and then applied to cognitive radio networks. Two examples are provided to verify the proposed new design method. (C) 2018 Elsevier Ltd. All rights reserved.