Fuel injector comprising a nozzle and a control valve, the injector body comprising inter alia the valve body and the nozzle body, in which a needle that can move between an entirely open position and a closed position and a metal spring compressed between a bearing surface secured to the nozzle body and a shoulder of the needle are arranged, the spring constantly pressing the needle toward the closed position, the injector being arranged in a way that, during use of the injector body is in electrical contact with the electrical ground, the nozzle comprising the nozzle body, an upper guide and a lower guide, a valve body seat and injection holes, and also comprising the needle, which extends between a first end provided with a needle seat and a second end forming the head of the needle, the needle being arranged so as to slide between the upper guide and the lower guide and being capable of moving between the closed position, in which the needle seat is in contact with the valve body seat, fuel injection being prevented, and the entirely open position, in which the needle seat is separated from the valve body seat, injection being possible, the control valve comprising the valve body arranged fixed on the nozzle body so as to define together a control chamber in which the head of the needle is located, the movements of the needle being dependent on the pressure variations in the control chamber so that, in the entirely open position, the top of the head of the needle is in contact with a wall of the control chamber, said wall forming the roof of the control chamber, the injector furthermore being provided with a device for identifying the position of the needle, in which an electrical circuit is closed when the needle is in the entirely open position and also when the needle is in the closed position, the needle then being in electrical contact with the ground, the circuit being open in any other intermediate position (Pi) of the needle, the needle not being grounded, characterized in that the device for identifying the position of the needle makes it possible to generate a variable electrical signal representing the position of the needle, the device comprising the electrical insulation (Rie) of the surfaces of the needle, or of the injector body, which may be in contact with one another, except for the needle seat and the valve body seat, the top of the head of the needle and the roof of the control chamber, and the bearing shoulder of the spring on the needle and the bearing face of the spring secured to the nozzle body, and wherein the upper guide is integrated with the nozzle body, the interface between the nozzle body and the valve body being planar, the electrical device furthermore comprising a member in the form of a planar disk arranged between the nozzle body and the valve body, the disk being provided with an opening located just above the control chamber, the opening being slightly smaller than the control chamber so that the disk extends at the periphery of the roof of the control chamber, the disk being formed by a metal disk provided with an electrically insulating coating (Rie) on its two opposite faces, except for the perimeter of the opening located at the periphery of the roof, an insulator-free surface against which the spring bears, so that in the entirely open position the head of the needle extends through the opening and its top is in contact with the roof of the control chamber.