Condition monitoring of permanent magnet synchronous motors (PMSMs) is the process that identifies and averts impending faults and is of critical importance for reliability and robustness of overall system. In this study, magnet defect fault in PMSMs and the consequence effects of such failure on stator back-emf and current wave forms are investigated through modified magnetic equivalent circuit (MEC). The proposed analytical approach is used to investigate the effect of magnet faults on the stator back-emf which significantly reduces the computational burden and provides high enough accuracy while predicting the additional harmonics in motor variables. The 2-D Finite Element (FE) results support the potential use of the proposed method for fault signature analysis. Simulations are also carried out at different speed and load condition to expose the faulty signature. Comparative experimental results conducted at the same conditions to show the efficacy of the proposed method.