The invention relates to a fluid valve, in particular for the exhaust gas from a motor vehicle engine, comprising a body (30) defining a main duct (31) and an auxiliary duct (32) for the flow of fluid, which auxiliary duct opens into the main duct (31). The valve also comprises: a flap (1) that can move between a closed position, preventing communication between the two ducts (31, 32), and an open position, allowing communication between said ducts (31, 32); and a gasket (2) against which the flap (1) bears when in the closed position. In addition, the above-mentioned body comprises a housing (37) for a motor for actuating the flap (1). According to the invention, the body (30) is configured to define a fluid lamina (38) between the gasket (2) and the housing (37).