System to regenerate a trap in the exhaust system for an internal combustion engine

A system for improving the regeneration of a depollution device (1) integrated in an exhaust line (2) of a heat engine of an automobile, by alternately operating the engine in lean and rich modes according to various control parameters for engine function, comprises a lambda probe (9) placed in the exhaust gas outlet of the motor, where at least one engine function parameter is controlled to regulate, in a closed loop, the richness of the exhaust gas at a target value when the engine functions in rich mode.