Hi = Steve,
 
Be sure to buy only VW's original = sensor with new tank.  Last spring I bought wild copy of the sensor (higher = price than VW's original as I noticed later).  The system seems to keep = coolant for 3 weeks..and then suddenly there was a large spot under the car.  = Sensor has melted shapeless (lower temp plastic?).  The VW's original has been = running well since that.

 
Juha Koivisto
88 Vanagon (Caravelle) 1,6TD (old = school bus with 9 seats)
TURKU, FINLAND