This paper presents a probe that permits the detection of longitudinal and circumferential defects in stainless steel tubes. The defect detection is made by a measurement system based on eddy current (EC) and remote field testing (RFT). The probe includes an excitation coil and a giant magneto-resistance (GMR) magnetic sensor. This GMR sensor has high sensitivity in a large frequency range (0 Hz–1 MHz) which makes it a good candidate to analyse several defects in tubes using a remote field testing method. Experimental data were acquired by a measurement system to verify the sensitivity of the GMR in defect detection and to create a new probe. A simulation was made in order to verify the veracity of the obtained experimental results when the remote field testing method is applied. Finally, 2D maps representing the GMR output response at several angles of rotation around the defects were made and compared in this paper.