Pressure reducer, having a housing, having a valve which is positioned in the housing, wherein the valve, in a closed state, separates an inlet pressure chamber of the housing from an outlet pressure chamber of the housing and, in an open state, connects the inlet pressure chamber and the outlet pressure chamber, wherein the valve has a diaphragm which acts on a valve plunger and on which, with provision of a pressure reducer function, a spring force of a spring element that acts in the opening direction of the valve, on the one hand, and a force which acts in the closing direction of the valve and is dependent on a pressure prevailing in the outlet pressure chamber, on the other hand, act, wherein the valve has a valve body which is fastened to the valve plunger and which, in the closed state, bears sealingly against a valve seat and which, in the open state, is lifted off from the valve seat, and wherein the spring element is arranged between spring plates (18, 19), specifically between a spring plate facing the diaphragm and a spring plate facing away from the diaphragm, having a sensor which is integrated into the pressure reducer and serves for detection of leakage, characterized in that the sensor is integrated into a non-fluid-conducting region of the pressure reducer in such a way that either the sensor is assigned to a portion of the valve plunger, or interacts with a portion of the valve plunger, that projects into the non-fluid-conducting region of the pressure reducer, or the sensor is assigned to the spring plate facing the diaphragm or interacts with the spring plate facing the diaphragm. having a housing, having a valve which is positioned in the housing, wherein the valve, in a closed state, separates an inlet pressure chamber of the housing from an outlet pressure chamber of the housing and, in an open state, connects the inlet pressure chamber and the outlet pressure chamber, wherein the valve has a diaphragm which acts on a valve plunger and on which, with provision of a pressure reducer function, a spring force of a spring element that acts in the opening direction of the valve, on the one hand, and a force which acts in the closing direction of the valve and is dependent on a pressure prevailing in the outlet pressure chamber, on the other hand, act, wherein the valve has a valve body which is fastened to the valve plunger and which, in the closed state, bears sealingly against a valve seat and which, in the open state, is lifted off from the valve seat, and wherein the spring element is arranged between spring plates (18, 19), specifically between a spring plate facing the diaphragm and a spring plate facing away from the diaphragm, wherein the valve, in a closed state, separates an inlet pressure chamber of the housing from an outlet pressure chamber of the housing and, in an open state, connects the inlet pressure chamber and the outlet pressure chamber, wherein the valve has a diaphragm which acts on a valve plunger and on which, with provision of a pressure reducer function, a spring force of a spring element that acts in the opening direction of the valve, on the one hand, and a force which acts in the closing direction of the valve and is dependent on a pressure prevailing in the outlet pressure chamber, on the other hand, act, wherein the valve has a valve body which is fastened to the valve plunger and which, in the closed state, bears sealingly against a valve seat and which, in the open state, is lifted off from the valve seat, and wherein the spring element is arranged between spring plates (18, 19), specifically between a spring plate facing the diaphragm and a spring plate facing away from the diaphragm, having a sensor which is integrated into the pressure reducer and serves for detection of leakage, characterized in that the sensor is integrated into a non-fluid-conducting region of the pressure reducer in such a way that either the sensor is assigned to a portion of the valve plunger, or interacts with a portion of the valve plunger, that projects into the non-fluid-conducting region of the pressure reducer, or the sensor is assigned to the spring plate facing the diaphragm or interacts with the spring plate facing the diaphragm.