Tom ,
             I had the same problem with a phantom
problem that kept the low coolant light coming on.
It seems that the pins that are in the sensor were
leaking coolant past the pins themselves because
the connector and connection points were always
wet with coolant. Once I replaced the sensor the
problem vanished. I think I paid about 16.00 at
the nearest VW dealer. You can probably get it
cheaper from one of the list vendors? Good luck!
 Tom Czerniak   87 Westy