A device includes at least one ammonia storage cartridge comprising an outlet orifice for ammonia intended to be connected to an ammonia transport circuit towards an exhaust line. The device includes an obturator to obturate the outlet orifice, and which is capable of changing between an obturation configuration of the outlet orifice and a configuration for clearance the outlet orifice. The device includes a detector to detect at least one predefined situation, and a controller to control the obturator, and which is capable of controlling the transition of the obturators towards their obturation configuration when the detector detects the predefined situation.