Pollution Sensing
WARNING: This page is about a different car, the 2006 Land Rover Range Rover Sport. However, it is still accessible from the selected car via links, so may be relevant.
With a pollution sensor fitted to the vehicle, the ATC module controls the intake air source to reduce contamination of the intake air by external pollutants. This function is fully automatic, but can be overridden by manual selection of the intake air source.