Abstract: A test system for examining a hollow body, in particular a cylinder bore in an engine block, comprises a measuring apparatus comprising an elongate body and a plurality of sensors which are connected to the body and are set up to carry out a distance measurement. The test system also comprises electronic control means which are set up to move the measuring apparatus into a hollow body to be examined and to determine an internal diameter of the hollow body on the basis of distance measurement data from the sensors. In order to examine hollow bodies of different diameters, at least some of the sensors are in the form of movable sensors which can be moved relative to the elongate body of the measuring apparatus. The electronic control means are also set up to select a measuring position of the movable sensors relative to the elongate body on the basis of a hollow body to be examined.