Turbo vent filter
Another one of those often over looked service items is the turbo vent filter; located towards to rear of the engine on the drivers side (Td4 RHD) changing it really couldn’t easier, carefully pull the existing filter from the small bore rubber hose it’s connected to (use a pull/twist action to prevent stressing the hose) and replace with the new filter taking care to ensure it’s fitted in the right orientation also note that the opposite end is intended to be left open to the atmosphere and not connected to anything, once fitted clip back in place to prevent any annoying rattles or chaffing.