WARNING: This page is about a different car, the 2013 Land Rover LR4, 2012 Land Rover LR4, 2011 Land Rover LR4, and 2010 Land Rover LR4. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
The piston and piston pin are a matched pair. Do not mix up the components.
Measure the piston pin diameter.
Measure the diameter in two directions.
If the values are not to specification, install a new piston and a new piston pin.