Check valve, in particular for a cooling or heating circuit, which is insertable into a connection opening (26, 27, 28, 29) of a connection device or a tube, - having a one-part or multi-part housing, which comprises at least one basic housing, wherein a feed opening is provided on the inlet side and a discharge opening is provided on the outlet side on the basic housing, which are connected to each other by a flow channel, - having a guide element provided on the basic housing, through which a valve closing member is displaceably guided to the basic housing, wherein the valve closing member is arranged in an initial position by means of an energy storage element, and the valve closing member is displaceable in the direction of the discharge opening against an actuating force of the energy storage element in order to transfer into a working position, and - the energy storage element is provided between the valve closing member and the basic housing, - the guide element of the basic housing has at least one aperture, and at least one guide rod is guided in this at least one aperture, said guide rod extending from the valve closing member through the at least one aperture and being secured against disengagement from the aperture, - wherein the valve closing member, in the initial position and in a first opening phase, is guidable in the connection opening of the connection device or is guided in the connection opening (26, 28) of a valve housing of the housing by the at least one guide rod in the guide element and by at least one guide rib positioned on the closing body of the valve closing member in the opposite direction to the at least one guide rod, engaging in the connection opening of the connection device or is guided in the connection opening (26,28) of a valve housing, characterized in - that in the arrangement of the closing body of the valve closing member in its initial position or closing position, the outer surface of the closing body of the valve closing member is in positive contact with a valve seat, and a sealing element on the closing body downstream in the direction of flow only acts on the valve seat in a sealing manner, - that in a second opening phase, the valve closing member is guided to the working position by the at least one guide rod in the guide element and by a guide section surrounding the at least one guide rod on the valve closing member and the sleeve on the guide element and, - that as soon as the guide surfaces of the guide ribs on the closing body detach from the valve seat during the transition from a first opening phase to a second opening phase of the valve closing member, the guide section and the sleeve engage with each other and form an axial guide of the valve closing member. - having a one-part or multi-part housing, which comprises at least one basic housing, wherein a feed opening is provided on the inlet side and a discharge opening is provided on the outlet side on the basic housing, which are connected to each other by a flow channel, - having a guide element provided on the basic housing, through which a valve closing member is displaceably guided to the basic housing, wherein the valve closing member is arranged in an initial position by means of an energy storage element, and the valve closing member is displaceable in the direction of the discharge opening against an actuating force of the energy storage element in order to transfer into a working position, and - the energy storage element is provided between the valve closing member and the basic housing, - the guide element of the basic housing has at least one aperture, and at least one guide rod is guided in this at least one aperture, said guide rod extending from the valve closing member through the at least one aperture and being secured against disengagement from the aperture, - wherein the valve closing member, in the initial position and in a first opening phase, is guidable in the connection opening of the connection device or is guided in the connection opening (26, 28) of a valve housing of the housing by the at least one guide rod in the guide element and by at least one guide rib positioned on the closing body of the valve closing member in the opposite direction to the at least one guide rod, engaging in the connection opening of the connection device or is guided in the connection opening (26,28) of a valve housing, characterized in - that in the arrangement of the closing body of the valve closing member in its initial position or closing position, the outer surface of the closing body of the valve closing member is in positive contact with a valve seat, and a sealing element on the closing body downstream in the direction of flow only acts on the valve seat in a sealing manner, - that in a second opening phase, the valve closing member is guided to the working position by the at least one guide rod in the guide element and by a guide section surrounding the at least one guide rod on the valve closing member and the sleeve on the guide element and, - that as soon as the guide surfaces of the guide ribs on the closing body detach from the valve seat during the transition from a first opening phase to a second opening phase of the valve closing member, the guide section and the sleeve engage with each other and form an axial guide of the valve closing member.