A trailer control valve for a vehicle, comprising at least one lip seal, a first element, a second element formed as a piston, a valve inlet, a valve outlet, and a valve seat, wherein, in a closed position, said piston engages said valve seat and closes said trailer control valve, wherein, in an open position, said piston is spaced from said valve seat such that pressurized air can flow from said valve inlet to said valve outlet, wherein said lip seal is for sealing said first element against said second element moving relative to the first element, wherein said lip seal comprises: a ring shaped lip seal body, comprising a sealing portion for contacting said second element, and a fixing portion for fixing the lip seal to said first element, having an assembly groove formed in an outer peripheral surface for engaging with a corresponding protrusion formed on said first element and a transition portion to the sealing portion, the lip seal body being rotationally symmetrical to a central axis of the lip seal body, the sealing portion comprising an inner leg protruding towards the central axis and an outer leg protruding away from the central axis, wherein the outer leg is adapted to sealingly contact the first element and the inner leg is adapted to sealingly contact the second element, wherein, in order to prevent leakage, said inner leg engages said piston while said outer leg engages said first element, and wherein, during the operation of said trailer control valve, said piston slides relative to said inner leg, while said lip seal is fixed to said first element. wherein, in a closed position, said piston engages said valve seat and closes said trailer control valve, wherein, in an open position, said piston is spaced from said valve seat such that pressurized air can flow from said valve inlet to said valve outlet, wherein said lip seal is for sealing said first element against said second element moving relative to the first element, wherein said lip seal comprises: a ring shaped lip seal body, comprising a sealing portion for contacting said second element, and a fixing portion for fixing the lip seal to said first element, having an assembly groove formed in an outer peripheral surface for engaging with a corresponding protrusion formed on said first element and a transition portion to the sealing portion, the lip seal body being rotationally symmetrical to a central axis of the lip seal body, the sealing portion comprising an inner leg protruding towards the central axis and an outer leg protruding away from the central axis, wherein the outer leg is adapted to sealingly contact the first element and the inner leg is adapted to sealingly contact the second element, wherein, in order to prevent leakage, said inner leg engages said piston while said outer leg engages said first element, and wherein, during the operation of said trailer control valve, said piston slides relative to said inner leg, while said lip seal is fixed to said first element. a ring shaped lip seal body, comprising a sealing portion for contacting said second element, and a fixing portion for fixing the lip seal to said first element, having an assembly groove formed in an outer peripheral surface for engaging with a corresponding protrusion formed on said first element and a transition portion to the sealing portion, the lip seal body being rotationally symmetrical to a central axis of the lip seal body, the sealing portion comprising an inner leg protruding towards the central axis and an outer leg protruding away from the central axis, wherein the outer leg is adapted to sealingly contact the first element and the inner leg is adapted to sealingly contact the second element, wherein, in order to prevent leakage, said inner leg engages said piston while said outer leg engages said first element, and wherein, during the operation of said trailer control valve, said piston slides relative to said inner leg, while said lip seal is fixed to said first element.