A testing apparatus and a method for detecting a contact deficiency of an electrically conductive connection. The testing apparatus comprises a measuring chamber, in which several system elements of the connection that are connected in an electrically conductive fashion are positioned, a heat radiator that is supplied with energy and the transferred thermal radiation of which is emitted into the measuring chamber and directed toward the region of the system elements that, after having been heated, generate a thermal field of the insulated and the metallic system components of these connected system elements, a thermal (image) acquisition unit for optically capturing the generated thermal field and for realizing a signal conversion into a thermal image of the connected system elements, and a thermal (image) reproduction unit for the visual reproduction of the converted thermal image.