Thermostat Test
WARNING: This page is about a different car, the 2019 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.
Check the electric thermostat for loose or corroded connector(s), check the operation of the electric flow/direction valve(s). If the engine still does not maintain the correct temperature, check the operation of the internal wax type thermostat. Check and replace parts as necessary