A fuel injector for an internal combustion engine, the fuel injector comprising: a nozzle needle which is movable within a nozzle body (16, 16a) to control fuel delivery through an outlet; a control chamber for fuel defined, at least in part, within the nozzle body (16, 16a) so that an upper surface of the nozzle needle is exposed to fuel within the control chamber; and A valve housing comprising a control valve and being located above the nozzle body (16, 16a) having a lower surface including a first region located, in part, above or defining a contact region for the nozzle body (16, 16a) surrounding the control chamber, characterized in that the lower surface further comprises a relieved region further separated from the nozzle body (16, 16a), relative to at least the first region, so as create an increased contact pressure at the first region when the housing part and the nozzle body (16, 16a) are clamped together, relative to a lower surface in which there is no relieved region and wherein the lower surface includes a second region located above or defining a ceiling of the control chamber and, the fuel injector further comprising a spill path provided in the housing part which opens into the second region and provides a flow path for fuel out of the control chamber to a low pressure drain. a nozzle needle which is movable within a nozzle body (16, 16a) to control fuel delivery through an outlet; a control chamber for fuel defined, at least in part, within the nozzle body (16, 16a) so that an upper surface of the nozzle needle is exposed to fuel within the control chamber; and A valve housing comprising a control valve and being located above the nozzle body (16, 16a) having a lower surface including a first region located, in part, above or defining a contact region for the nozzle body (16, 16a) surrounding the control chamber, characterized in that the lower surface further comprises a relieved region further separated from the nozzle body (16, 16a), relative to at least the first region, so as create an increased contact pressure at the first region when the housing part and the nozzle body (16, 16a) are clamped together, relative to a lower surface in which there is no relieved region and wherein the lower surface includes a second region located above or defining a ceiling of the control chamber and, A valve housing comprising a control valve and being located above the nozzle body (16, 16a) having a lower surface including a first region located, in part, above or defining a contact region for the nozzle body (16, 16a) surrounding the control chamber, characterized in that the lower surface further comprises a relieved region further separated from the nozzle body (16, 16a), relative to at least the first region, so as create an increased contact pressure at the first region when the housing part and the nozzle body (16, 16a) are clamped together, relative to a lower surface in which there is no relieved region and wherein the lower surface includes a second region located above or defining a ceiling of the control chamber and, the fuel injector further comprising a spill path provided in the housing part which opens into the second region and provides a flow path for fuel out of the control chamber to a low pressure drain.