V40 D4 2015 48k miles. Coolant Low Warning.
 

Our V40 D4 from 2016 with 48,000 miles has just started showing the coolant level low warning.

Have seen that the coolant level is low with a cold engine, but once the engine warms up the coolant level increases to over half in the expansion bottle. The fan does not come on, there are no messages about engine overheating.

I've seen references to faulty sensors, water pump issues, head gaskets and cracked engines in relation to this issue.

Is there anything I can do further to diagnose the issue or determine what the likely cause is?
Should I drive it to my local dealer or call Volvo assist and have it recovered?

Thanks in advance.

All Resolved
 

The issue was just a minor leak, all sorted via Volvo On Call. Paid for new part and coolant but no labour so very good service.

Which part was leaking?

The radiator return hose. Thin narrow hose that goes across the top of the radiator to the expansion bottle. It had fallen down by the fan and had some pin prick holes in it from the fan.
Seems likely it fell after being dislodged when then the car was repaired a couple of years ago by a Volvo dealer under warranty. The car hasn't been used that much due to Covid since the repair.