Fuel injector comprising a nozzle and a control valve, feed body of the injector comprising, among other things, the body of the valve and the body of the nozzle as well as a top guide which is an independent part arranged between the nozzle body and the valve body and in which there are arranged a needle that is mobile between a fully opened position and a closed position and, a metal spring compressed between a bearing surface integral to the top guide and a shoulder of the needle, the spring permanently stressing the needle towards the closed position, the injector being arranged so that, in use, the injector body is in electrical contact with the electrical ground, the nozzle comprising the nozzle body, the top guide and a bottom 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 to slide between the top guide and the bottom guide and being able to be displaced between the closed position in which the needle seat is in contact with the valve body seat, the injection of fuel being prevented, and, the fully opened position in which the needle seat is separated from the valve body seat, injection being possible, the top guide and the valve body together defining a control chamber in which the head of the needle is located, the displacements of the needle being a function of the pressure of variations in the control chamber such that, in fully opened position, the top of the head of the needle is in contact with a wall of the control chamber, said wall forming the ceiling of the control chamber, the injector is also provided with a device for registering the position of the needle in which an electrical circuit is closed when the needle is in fully opened position and also when the needle is in closed position, the needle then being in electrical contact with the ground, the circuit being opened in any other intermediate position (Pi) of the needle, the needle not being connected to the ground, in which the device for registering the position of the needle making it possible to generate a variable electrical signal that is representative of the position of the needle comprises electrical insulation (Rie) of the surfaces of the needle or of the injector body that can be in contact with one another, apart from the needle seat and the valve body seat, from the top of the head of the needle and from the ceiling of the control chamber and from the shoulder by which the spring bears on the needle and the bearing surface integral to the top guide, the electrical link also comprising an annular disc interposed between the spring and the top guide, a face of said disc being said bearing surface of the spring and, the interface between the annular disc and the top guide being electrically insulated (Rie), the needle passing through a central aperture of the annular disc so that, in fully opened position, the head of the needle is in contact with the ceiling of the control chamber and, in which the top guide is provided with a duct passing right through it, a link tab being conformed to extend from the annular disc into said duct, characterized in that the electrical link also comprises an intermediate connection link extending through said duct passing through the valve body to an end connected to the annular disc, which duct is sealed and electrically insulated.