There is a sensor guide wire (1) for intravascular measurements of physiological variables in a living body. The sensor guide wire (1) comprises at least two elongate sections, a first tubular elongate section (2) being tubular in the longitudinal direction of the sensor guide wire (1), and a second elongate section (3) that is adapted to be inserted a predetermined distance (5) into said first tubular section (2), a sensor element (10) provided in the distal part of said sensor guide wire (1), for measuring the physiological variable and to generate a sensor signal in response to said variable, at least one signal transmitting cable connected to the sensor element (10) to transmit sensor signals to a male connector provided in the proximal part of said sensor guide wire (1). The tubular section (2) is provided with at least one through-going opening (4) in a direction perpendicular to the longitudinal direction of the guide wire (1) and positioned a second predetermined distance (6) from one end of the tubular section (2), wherein the guide wire (1) comprises a locking member (7) to be fitted into the opening (4) in order to join the sections (2, 3) together when the second elongate section (3) is inserted into the tubular section (2).