The invention relates to a process, consisting in cooling at least one component, such as a sensor, arranged within a compartment of an exhaust after treatment system of a vehicle. The exhaust after treatment system comprises a cooling system that is activated during active regeneration of one or more particulate filters arranged within the exhaust after treatment system compartment and that includes a pipe, for blowing fresh air on the component to be cooled or for extracting hot air present at the vicinity of the component to be cooled, so that said component is protected as a priority against high temperatures during active regeneration periods.