This paper investigates the problem of fault detection for uncertain switched fuzzy systems with unmeasurable premise variables. A dissipativity-based fault detection observer is designed. The observer order can be adjusted within a certain range. By solving a set of linear matrix inequalities, the sufficient condition can be obtained to ensure that under arbitrary switching signal, the residual dynamic is strictly (Q, S, R)-κ-dissipative. Furthermore, the elaborate H ∞ . performance and the elaborate H_ performance are obtained, which can be treated as expansions of the traditional H ∞ . performance and H_ performance. The parameter uncertainties are decoupled from the residual. Simulation results are presented to verify the proposed techniques.