Hi, would LR diagnostics machine tell if the rear diff is faulty, or would it need a mechanic to physically diagnose it?
Thank you

I would have thought that the diff is a purely mechanical device, so no.

But the Haldex unit is close coupled to the diff, this has electronics that can throw up fault codes.
So in my humble opinion, if it's the diff which is purely mechanical it is unlikely that the diagnostics can reliably detect a fault, if on the other hand it is actually the Haldex that is playing silly then yes most faults will show up with diagnostics. Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Thank you Andy