During metallic wire drawing processes, the presence of knots and the failure to detect them can lead to long production interruptions, significant economic losses and a lower quality of final product. Consequently, there is a pressing need to develop methods for real-time detection and prevention of this fault. In this paper a sensor to prevent the formation of knots during the metallic wire drawing process is presented and evaluated by means of experimental data. This fast, inexpensive, non-contact sensor is based on electromagnetic principles such as eddy current induction, magnetic reluctance variations and magnetic coupling. The proposed sensor can detect knots in a target metallic wire without direct contact by measuring the impedance variations of a calibrated sensing coil caused either by a knot or an unwound loop rising from a wire rod. The incorporation of this type of sensor into a wire drawing machine can avoid the tightening of the knot, thereby reducing downtime and increasing the security and reliability of the process. Experiments were conducted using a scale model of the above proposed system. This allowed to highlight the sensor’s potential by carrying out an automatic, real-time knot detection during steel wire drawing.