Method and device for managing the operation of the trap to nitrogen oxides for a internal combustion engine operating with a lean mixture.

According to this method, there is a first oxygen sensor (21) on the exhaust downstream of the trap nitrogen oxides conduit (18), and observed the evolution of a significant signal representative of the signal (3, 4) supplied by this probe, a significant increase (34, 44) of said significant signal from a first plate (32, 42) of substantially constant level, obtained after a variation (31, 41) following a passage the engine of a lean mixture operation to rich mixture operation, is used as an indicator to order the end of the purge.Application diesel engines.