Low coolant level alarm on 2010 D4

[wombathole]

I'm getting "low coolant level" alarms but when I check, my expansion tank is full. My temp is between 100 and 106c. From reading about similar on aulro and disco3, sounds a lot like the d3 issue where the float in the exp tank saturates and sinks.
Do the d4's have this same float issue?
If yes, is there a way to visually check that the float is the cause? I've looked but can't see a float.
If not, any idea what is the cause of this seemingly erroneous alarm?

[incisor]

have you changed coolant just before this started occurring ?

[wombathole]

About 3000 km ago the plastic coolant junction broke and was replaced. The expansion tank emptied in the process.

[scarry]

My indie mechanic told me whenever he does a coolant flush,he changes that float.

They play up intermittently,often after a coolant flush.

[hv_man]

Hi
I've just replaced mine.
This is a common problem that happens with age and is not repairable. Only solution is to replace the whole expansion tank.
Pretty easy to do..
Atlantic British Presents: Coolant Expansion Tank Install on 2006 Range Rover - YouTube (https://youtu.be/WSU3H10YfGc)

[hv_man]

My indie mechanic told me whenever he does a coolant flush,he changes that float.

They play up intermittently,often after a coolant flush.

The float is not accessible it's sealed inside the bottom chamber of the expansion tank.

[wombathole]

FYI update. I haven't replaced the expansion tank yet and driven the d4 from Atherton to Fraser Island (~2000km with side trips). I bled a little air pocket out the top of the expansion tank, been watching temp closely (running at about 98c via iidtool) and the alarm has gone away for now...