Fault detection using a novel approach based singleton interval type 2 fuzzy sets is presented in this paper. The main idea of introduced method is based the concept of type-2 fuzzy sets. Residual signal could be constructed using this concept and evaluation of it can be done as well. The benefits of the proposed method have been presented by a well-known benchmark problem. Simulation results depict that the proposed fault detection method is highly effective tool in fast fault detection of nonlinear systems.