A few months ago I thought the coolant level was dropping. It was. When we went
from a waterboxer to a EV I thought we would escape the horrors of cooling
system problems. But a closer look showed that it wasent the head gasket after
all !! Just a small plastic fitting on the side of the head, PN 074 121 143B.

The problem is/was that this fitting is held on by only one bolt. Not two (one
on each side) but one only on one side. It had cracked and then partly extruded
its O-ring. It was not leaking much but just a slight drip at operating temp.

And just blow me away, the dealer had one in stock. About $8. It is also used on
some more normal VW's and "goes all the time" so they said.

Not an easy part to get at. Took me 3 hours ( drain and refill coolant too.)