I've been told that the tubo's vnt mechanism fails or sticks. Can this be checked via the diagnostic port?

Check, when it's working, no. Or at least not directly.
Read an error about it, when it fails, yes.

I use Forte Diesel Treatment then a tank later put in Forte Turbo Cleaner for diesels, my land rover specialist highly recommends it 105,000 miles without a single turbo problem

Mine had to have a new actuator fitted when I bought it, not sure if this relevant to your question or not, done by Central Turbos in Derby. FL2 SD4 Metropolis Auto Santorini Black / ivory completely stock.

It's true that light travels faster than sound, some people look quite intelligent until you hear them speak.


Stop global winging.