Filter for purifying a liquid for an internal combustion engine, in particular lubricating oil, comprising: - a housing having an inlet for unprocessed liquid and an outlet for purified liquid, the housing defining an interior volume and comprising a cover that can be detached from the rest of the housing, the inlet and the outlet being formed a the opposite from the cover, in a bottom portion of the housing; - a filter insert, which extends longitudinally between a distal first end of the outlet and a proximal second end of the outlet, adapted to be removably received within the interior volume by engaging in the bottom portion and comprising: - a filter medium of annular shape which extends around a central axis defining a longitudinal axis of the filter insert; - a flange, located towards the first end, for covering one axial end of the filter medium; - a bypass valve forming a preassembled unit and secured to the filter insert, the bypass valve being interposed, within the interior volume towards the first end, between a region upstream of the filtration that is in communication with the inlet and a region downstream of the filtration that is in communication with the outlet; the bypass valve being integrally secured to the cover by a connection system; characterized in that the bypass valve: - is detachable from the cover so that the assembly formed by the filter insert and the bypass valve defines a removable cartridge, - forms a preassembled unit, and has at least one removable connection member which: - in a locking configuration, is axially engaged with complementary securing means formed on the first end of the filter insert, the complementary securing means being formed on the flange to which the bypass valve is directly attached, and - allows subsequent disassembly of the bypass valve from the filter insert; and in that the bypass valve is adapted to be integrally secured on the first end, by a locking action which is carried out by pivoting the bypass valve and the filter insert relative to one another about the central axis, said removable connection member being formed, in a locking configuration, higher and thus more distant from the bottom portion than a sealing region defined by the annular radial contact of a sealing member between the flange and the bypass valve, being axially engaged with the complementary securing means. - a housing having an inlet for unprocessed liquid and an outlet for purified liquid, the housing defining an interior volume and comprising a cover that can be detached from the rest of the housing, the inlet and the outlet being formed a the opposite from the cover, in a bottom portion of the housing; - a filter insert, which extends longitudinally between a distal first end of the outlet and a proximal second end of the outlet, adapted to be removably received within the interior volume by engaging in the bottom portion and comprising: - a filter medium of annular shape which extends around a central axis defining a longitudinal axis of the filter insert; - a flange, located towards the first end, for covering one axial end of the filter medium; - a filter medium of annular shape which extends around a central axis defining a longitudinal axis of the filter insert; - a flange, located towards the first end, for covering one axial end of the filter medium; - a bypass valve forming a preassembled unit and secured to the filter insert, the bypass valve being interposed, within the interior volume towards the first end, between a region upstream of the filtration that is in communication with the inlet and a region downstream of the filtration that is in communication with the outlet; the bypass valve being integrally secured to the cover by a connection system; - is detachable from the cover so that the assembly formed by the filter insert and the bypass valve defines a removable cartridge, - forms a preassembled unit, and has at least one removable connection member which: - in a locking configuration, is axially engaged with complementary securing means formed on the first end of the filter insert, the complementary securing means being formed on the flange to which the bypass valve is directly attached, and - allows subsequent disassembly of the bypass valve from the filter insert; - in a locking configuration, is axially engaged with complementary securing means formed on the first end of the filter insert, the complementary securing means being formed on the flange to which the bypass valve is directly attached, and - allows subsequent disassembly of the bypass valve from the filter insert; and in that the bypass valve is adapted to be integrally secured on the first end, by a locking action which is carried out by pivoting the bypass valve and the filter insert relative to one another about the central axis, said removable connection member being formed, in a locking configuration, higher and thus more distant from the bottom portion than a sealing region defined by the annular radial contact of a sealing member between the flange and the bypass valve, being axially engaged with the complementary securing means.