I have, once again, replaced the 251 919 372 Coolant Level Sensor to fix
the blinking red light in the Coolant Temperature Gauge in my '86
Westy.�  It is most annoying that this excessively high priced sensor has
to be replaced on a regular basis.�  Certainly VW could have figured a
way to measure coolant level rather than with this sensor.�  I have had
to replace this sensor regularly about every 10 years and the cost has
now reached the exorbitant level of $1.80.�  The list price from one
vendor is actually $42.44.

When replacing the sensor this time I made an observation that might
help us all avoid this expensive repair.�  When the old sensor was
removed I noticed one of the sensing pins was bright and clean while the
other was black and rough.�  Since the level gauge measures resistance
between the submerged pins there must be a constant small current
passing through the coolant between the pins.�  This constant current may
be removing ions from one pin and depositing them on the other, thus
changing the electrical activity of the surface of both.�  After 10 years
the difference might be enough to fool the electronic circuitry and
cause a false positive blinking light.

Has anyone else noticed this difference in appearance of the used sensor
pins?

I suggest that the electrical connections to the sensor be reversed on a
regular basis to keep the pins in equal, clean condition.�  The
electrical plug is not keyed to fit in the sensor so this is an easy
thing to do by rotating it 180 degrees.�  Doing this often will not be
detrimental so maybe at each oil change would be easy to remember.�  Or
maybe just do it once now and forget about it.

Just my Vanagon experience today.

Ed