[DriverDen]

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.