Abstract: A sensor is provided that can be used for measuring the internal pressure of injection lines of diesel engines includes two housing parts that are connected via a joint and can be clamped to the injection line using a clamping device. At least one electrical measuring element is pressed, in essentially uniform elastic fashion, onto the surface of the hollow body to be measured. The sensor also includes a support element that operates essentially in radial fashion. A protective film is arranged between the surface and the measuring element. The protective film has a thickness greater than or equal to the radial dimension of foreign bodies or the like that are to be expected on the surface of the hollow body to be measured. The protective film consists of plastic with a low modulus of elasticity.