A method for managing a pollution control system, driven by a computer, of a powertrain of a motor vehicle, this powertrain including: - an internal combustion engine having at least one cylinder supplied with fuel, via a fuel injector driven by the computer which controls the fuel injection or the cut-off of this injection; - an exhaust line of the gases originating from the combustion; the pollution control system including: - a reservoir containing a pollution control reducing agent; - a catalyzer integrated in the exhaust line so as to be passed through by the exhaust gases; - a reducing agent injector, placed upstream of the catalyzer and driven according to an open state permitting communication to be established between a pipe and the exhaust line, and a closed state permitting the suspension of the communication between the pipe and the exhaust line; - the pipe connecting the reservoir to the reducing agent injector; - a pump controlled by the computer, and arranged so as to function in a primary direction to introduce the reducing agent, via the reducing agent injector, within the exhaust line, and in a secondary direction to purge the reducing agent injector and the pipe; this method including taking into account at least the following parameters: - general status of the engine: in operation or stopped; - temperature in the vicinity of the pollution control system; characterized in that this method also includes taking into account the following parameters: - status of the cylinder (s): injection or cut-off of injection; - parameter linked to the composition of the gases present within the exhaust line; and in that it includes an actuating operation of the pump in its secondary direction if the following conditions are jointly verified: - engine in operating state; - cylinder(s) in injection cut-off state; - temperature in the vicinity of the pollution control system less than or equal to a predetermined value; - parameter linked to the composition of the gases equal to a predetermined setpoint; and an actuating operation of opening of the reducing agent injector. - an internal combustion engine having at least one cylinder supplied with fuel, via a fuel injector driven by the computer which controls the fuel injection or the cut-off of this injection; - an exhaust line of the gases originating from the combustion; - a reservoir containing a pollution control reducing agent; - a catalyzer integrated in the exhaust line so as to be passed through by the exhaust gases; - a reducing agent injector, placed upstream of the catalyzer and driven according to an open state permitting communication to be established between a pipe and the exhaust line, and a closed state permitting the suspension of the communication between the pipe and the exhaust line; - the pipe connecting the reservoir to the reducing agent injector; - a pump controlled by the computer, and arranged so as to function in a primary direction to introduce the reducing agent, via the reducing agent injector, within the exhaust line, and in a secondary direction to purge the reducing agent injector and the pipe; - general status of the engine: in operation or stopped; - temperature in the vicinity of the pollution control system; - status of the cylinder (s): injection or cut-off of injection; - parameter linked to the composition of the gases present within the exhaust line; - engine in operating state; - cylinder(s) in injection cut-off state; - temperature in the vicinity of the pollution control system less than or equal to a predetermined value; - parameter linked to the composition of the gases equal to a predetermined setpoint;