I had this issue on my 4.4 TDV8.

Swapping this valve did the trick. I swapped the whole valve rather than just the innards like in the video - a bit fiddly, but doable with the usual amount of RR swearing, dropping things into the black hole and trying not to break anything else in the process.

All toasty and warm again now!

?si=wSwtEa8A52im-0aM -------------------------
2012 4.4 TDV8 Vogue
2001 Audi A2 1.4 16V
2019 Skoda Kodiaq (don't ask...)

Looks like mine should be the same fix then, where did you get the valve? I’m assuming an aftermarket one as the guy on YouTube says the JLR ones are expensive, do you have a link so I know what I’m looking for. Many thanks Best Regards Lee

The part number is LR016848. I bought one on Amazon of all places! Cost was around €35. -------------------------
2012 4.4 TDV8 Vogue
2001 Audi A2 1.4 16V
2019 Skoda Kodiaq (don't ask...)

Much appreciated 👍 Best Regards Lee