Thermostat was Calorstat by Vernet. I still have the one I removed. Genuine I think. Thermostat changed because of leak not sensor.
I could put the old sensor back and see how that works

Thanks for comments and suggestions.
I did remove the sensor plug (on thermostat) check wires for obvious faults but none found. Refit plug. Thermostat is aftermarket.
After driving car today guess what. No more fan running on. Nothing else has changed.
Arguably not quite so hot today but still ...

Hi, XC90 2004 D5 Diesel (UK)
Recently I replaced my thermostat unit, thermostat plus holder, to fix a coolant leak problem. Leak fixed, temperature always stable at correct value.
Now, during our little UK heatwave I have noticed that after switching off (hot) engine the radiator fan continues to ...

XC90 2004 D5 2.4 diesel 163 bhp (RHD UK) 198,000 miles
About 3 months ago I started to see a small coolant loss. Maybe due to slight weeping from top up bottle beginning to crack but nothing visible anywhere in/under engine, or inside car floor pans .
That has changed quite suddenly. Today in the ...