It is probably the coolant tank sensor leaking. If you lift your deck
lid, it is the coolant tank to the left of the tank you see when you
pull the license plate. On top of the coolant tank there is a sensor.
You have to carefully remove the wire around the sensor and unplug it.
The you can replace the sensor or see if the is any coolant on the
electrical connectors and dry it out.
Just my 2 cents,
Steve Hajasz
90 Vanagon
90 Vanagon GL
84 Rabbit
And a storage unit filled with air cooled Beetle parts