Is it actually losing coolant? as the coolant level low message is a common fault, fixed by either changing the sensor or the coolant reservoir itself.

thank you for the reply, no, not losing coolant

It’ll probably be the sensor, easier to change the whole coolant reservoir.

It’s not unusual for a failing oil cooler to contaminate the coolant with oil which then shows up in the expansion tank, requiring replacement as part of the job, as well as a thorough flushing of the system.

Was your tank changed, perhaps the sensors electrical connector hasn’t been pushed home fully? Jonathan

2007 Defender 90 XS Hardtop

Change the tank, its £30ish and they often fail when you drain the coolant to perform a job...