Graphite Clamps
WARNING: This page is about a different car, the 2015 Jaguar XF, 2014 Jaguar XF, and 2013 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.
The graphite clamps are to prevent the ingress of air (oxygen) that would otherwise lead to false values being detected by the mid- and post catalyst HO2S. This will result in fuel trimming errors and misdiagnosis of catalyst condition.