A filter system comprising a housing, a fluid inlet formed in a housing wall, a fluid outlet formed in a housing wall, a primary filter element and a secondary filter element, both being accommodated in the housing, wherein the secondary filter element is arranged downstream the primary filter element on a stand pipe, a first axial end of the stand pipe being rigidly connected to one of the housing walls, the inside of the stand pipe being in fluid connection with the fluid outlet, a top region of the stand pipe positioned axially opposite the first axial end and comprising one or more connection elements configured to connect to connection elements of the secondary filter element, wherein the secondary filter element comprises a filter medium forming a body having at least one longitudinal seam along a longitudinal axis, wherein the secondary filter element comprises an end cap at its top region, wherein the end cap is provided with one or more connection elements configured to connect to the stand pipe connection elements, wherein the secondary filter element and the stand pipe are mutually connected by the connection elements (22, 156), and wherein the end cap of the secondary filter element and the stand pipe are configured with mutual self-positioning elements (30, 180) to arrange the secondary filter element on the stand pipe in a defined rotational position with respect to one or more struts of the stand pipe, characterized in that the mutual self-positioning elements (30, 180) comprise a guiding surface and a projection element, wherein the guiding surface is intended to guide the projection element from an initial position to a final position where the secondary filter element is in its defined rotational position with respect to the one or more struts of the stand pipe. wherein the secondary filter element is arranged downstream the primary filter element on a stand pipe, a first axial end of the stand pipe being rigidly connected to one of the housing walls, the inside of the stand pipe being in fluid connection with the fluid outlet, a top region of the stand pipe positioned axially opposite the first axial end and comprising one or more connection elements configured to connect to connection elements of the secondary filter element, wherein the secondary filter element comprises a filter medium forming a body having at least one longitudinal seam along a longitudinal axis, wherein the secondary filter element comprises an end cap at its top region, wherein the end cap is provided with one or more connection elements configured to connect to the stand pipe connection elements, wherein the secondary filter element and the stand pipe are mutually connected by the connection elements (22, 156), and wherein the end cap of the secondary filter element and the stand pipe are configured with mutual self-positioning elements (30, 180) to arrange the secondary filter element on the stand pipe in a defined rotational position with respect to one or more struts of the stand pipe, characterized in that the mutual self-positioning elements (30, 180) comprise a guiding surface and a projection element, wherein the guiding surface is intended to guide the projection element from an initial position to a final position where the secondary filter element is in its defined rotational position with respect to the one or more struts of the stand pipe.