I've seen a couple of these leak on Boxster/Cayman but now come across it on a 991.
If you have to top up the coolant then this is one area to have a look at .
The pressure bleed valve on the coolant tank leaks .. see images ..
If you have to top up the coolant then this is one area to have a look at .
The pressure bleed valve on the coolant tank leaks .. see images ..