Disclosed is a method for controlling depressurization in a fuel tank of a motor vehicle, including: the initial controlled opening of the isolation valve in order to lower the pressure inside the tank; determination of a blockage condition in the roll over valve on the basis of at least one item of information relating to the pressure gradient in the tank following the initial opening of the isolation valve; and, if the roll over valve blockage condition is met, the controlled closing of the isolation valve, followed by its controlled re-opening in order to continue lowering the pressure in the tank.