This paper is dealt with the fault detection (FD) problem for a class of network-based nonlinear systems with communication constraints and random packet dropouts. The plant is described by a Takagi-Sugeno fuzzy time-delay model, it has multiple sensors and only one of them is actually communicated with the FD filter at each transmission instant, and the packet dropouts occur randomly. The goal is to design a FD filter such that, for all unknown inputs, control inputs, time delays and incomplete data conditions, the estimation error between the residual and 'fault' (or, more generally, the weighted fault) is minimized. By casting the addressed FD problem into an auxiliary H ∞ filtering problem of a stochastic switched fuzzy time-delay system, a sufficient condition for the existence of the desired FD filter is established in terms of linear matrix inequalities. A numerical example is provided to illustrate the effectiveness and applicability of the proposed technique.