On Facebook, look for the GAP diagnostics IID tool user group which is a great resource

GAP Diagnostic is proud to be part of the Land Rover community by actively participating and sponsoring the following forums

These are United Kingdom based forums but do have many users from around the globe

To all Discovery 3, LR3, Discovery 4 and LR4 owners, this is the most complete and active forum known to us. Most of the information on this forum will also apply for the Range Rover Sport since both platforms are very similar

This would be the Range Rover Sport counterpart

The Defender forum

For Freelander 2 and LR2 owners

And for the Full Size Range Rover owners

In Australia

Aulro is the Australian reference forum for Land Rovers.

In America

RangeRovers.net as long been a great resource for both the Range Rover and Range Rover Sport. Some of its content also apply to Discovery 3/4 and LR3/LR4 since the platforms are similar