Abstract: In an injector for an accumulator injection system comprising an injector having an injector housing with an injection nozzle and an actuator for operating the injection nozzle arranged in a fuel-filled pressure space of the injector housing wherein the actuator includes a piezoelectric element disposed between an actuator head and an actuator the base with a fuel-tight casing at least partially surrounding the actuator head and the actuator base, the casing is engaged in a sealing fashion by a first annular element with the actuator base and by a second annular element with the actuator head.