In a message dated 97-08-28 07:26:12 EDT,
johan.nyberg@SODERTALJE.MAIL.TELIA.COM (Johan Nyberg) writes:

<< I have a problem with the coolant level warning light. Sometimes it goes
on
 flashing for a very long time (5 minutes or so) after the engine is started
 and running. Eventually it stops, and I don't have any trouble with the
 actual coolant level. I've replaced the sensor, the one with the two
 plastic covered metal prongs, with a used one that was thoroughly cleaned
 before installation. Problem is still there. Strange thing is that when I
 pull the connector on the sensor and turn on the ignition, the light
 flashes for a short time and then stops. The same thing happens if I pull
 the "black box" that is supposed to control the system (#3 on the relay
 board). My repair book doesn't cover this system at all, just tells it is
 there. >>

Johan,

I've seen this on a couple of Jettas. I'm sure (knowing VW) it is exactly the
same sensor and same problem/remedy.

A LITTLE-TINY-ITTY-BIT of coolent is leaking inbetween the sensor connection
prongs through a LITTLE-TINY-ITTY crack in the plastic. Look under the wiring
boot and you will see a LITTLE-TINY-ITTY-BIT of crud from all the coolent
that has died and gone to heaven from that very spot.

Your sensor light flashes untill the LITTLE-TINY-ITTY-BIT of coolent
evaporates away because the tank has gotten hot. Any coolent that
subsequently seeps out while you are out sightseeing evaporates away
immediately and does not conduct current between the  prongs, until you park,
the tank cools, and a couple of drops condense on the prongs again.

Replace the sensor AGAIN, then mark your calendar. Same time within two
years, you'll need another.

be cool, like Fonzie,

gmbulley
fairfax, va