Over temperature warning?
 

My V40 does not have a temperature guage. Is there an over heat warning built in any other way? Red light or buzzer maybe? Recently my radiator had a leak and the water was low, only noticed because the radiator fan was blowing after engine switch off, very unusual. Just wondered how hot it has to be to bring on any warning signal?

The next step would be a supplementary temperature guage.

I would add a temperature gauge myself, always better to be able to see what is normal to be able to spot a problem.