Fault diagnosis of electric motors is still a challenging task for researchers. Various rotor cage faults detection techniques for electric motors have been proposed during the last two decades. One of these techniques widely used is the one based on the stator current spectral analysis which is still an open topic of research. This paper focusses on this technique; which has proven to be simple and very practical for broken rotor bar faults diagnosis; but by adding further enhancements; particularly for incipient faults; so as to achieve better diagnosis reliability. The proposed enhancements are the design and realization of a low-pass filter, the development of a maximum localization algorithm and the use of a Hanning window in the PSD estimation. Some experimental results are presented and discussed to highlight the impact and merits of these enhancements on broken bar faults diagnosis.