A system for controlling the function of a diesel engine (1) in a motor vehicle having anti-pollution means (6, 7) includes an oxidation catalyst (6) and arranged in the exhaust system (3) of said engine (1). The catalyst (6) has at least one non-initialized state and one initialized state and the engine (1) has means (8) for supplying the engine cylinders with fuel with at least one injection during the recovery phase thereof. The system includes a single temperature sensor (18) downstream of the catalyst (6) and means (19) for controlling the supply means (8) by switching of the phase control and/or the quantity of fuel injected during the recovery phase between a first value for the initialization of the catalyst and a second value for maintaining the initialized state of the catalyst as a function of the measured temperature downstream of the catalyst.