Coolant Temperature Warning

Hi everyone,
2007 R55 Cooper S
I am getting the temp warning when car is under load usually uphill.
Has had the following work done, cylinder head rebuilt, new thermostat housing, water pump and radiator, bottom end has also been rebuilt.
Thermostat housing (genuine mini part) has been replaced again and I am still having issues.
Can anybody suggest anything to be checked. What I will say is I have a Bluetooth elm327 which shows temp going to 120oC which flags up the warning then within around 5 seconds temp drops to around 95oC
Any suggestions would be appreciated
Davie

I take it you’ve checked coolant levels? Also made sure that the system has been bled properly

Checked coolant level and it is OK, been refilled using vacuum bleeder

The other thing to consider is the temp sender functionality ok ,could be a faulty sender if everything else is ok

Been back out to check coolant level, would appear to have coolant forced out of cap as droplets of coolant on the underside off the bonnet, thinks I may have to bleed system again

To help anyone else in the future, turned out to be fault ambient temperature sensor. This was related to fault code 2f22 hope this may help someone in the future.

Great that you have it sorted

Pleased it’s sorted