93 Fox - Coolant warning light

When you restarted the car after the 3-days of it sitting, did it do the light/peg-the-needle thing immediately?

If so, sounds like a bad sensor.

If it took a while to do it, it might be your thermostat is only partially opening and the engine is getting far hotter than the radiator (the radiator fan is usually triggered by a sensor on the radiator and the temp gauge is usually near the head). And of course check your coolant level...maybe it all leaked out? (You didn't say if you had checked it or not...)

Not sure about the Fox but since it's a Golf/Jetta 1.8 engine and Digifant, the sensor might be like my GTI where it's in a fitting between the 3rd and

4th cylinders on the head, above and between the 3rd and 4th spark plugs. There may be a blue sensor and a black one. Blue is the temperature sendor to the Digifant unit and the black one is the one to the gauge (I'm pretty sure that's it). They're pretty inexpensive actually. Each sensor on my GTI just clips in. Make sure you get a new o-ring with it too. You might even want to replace both of them if they're inexpensive. Make sure you do it when the car is stone-cold or you risk losing more coolant (even cold a little bit will dribble out). Make sure you use distilled water when refilling and/or the correct coolant.

Did you check the coolant level. Always start with the basics!

Er what's wrong with using non-distilled water??? My hoses went and needed replacing at work so i used crappy water from two giant water towers that are from the second world war. is that bad?

did i forget to mention we also have to drink that water?

How long do you think "use distilled water when refilling and/or the correct coolant." stays distilled with all that aluminum and cast steel engine parts?

you talking about iron oxide here? or fungi, i dont think fungi can live in coolant can it?

I'm not a fan of putting tap water into an engine because of whatever impurities are in it. Even though it's safe to drink, it's still not really pure.

Stays closer to distilled than if you use tap water.

The majority of the VW coolant bottles use resistance to determine if the coolant is low or not. There are 2 probes in the bottle and if the coolant drops below where it no longer touches the probes the coolant lamp starts to flash. Try this the next time you change the coolant. With the old coolant still in the system unplug the sensor and measure the resistance(ohms) at the sensor... then do you coolant change + distilled water, run the engine for a bit and recheck the resistance! Might be surprised...

Correct always checked with basics. I had same problem few month back and it turn to be coolant was leaking from one of the hose pipe. Hose pipe was good however there was a plastic piece which was cracked and got replaced.

Also check if coolant cap is not lose that also bring light on.

Chlorine (in tap water) is bad for Al! It can initiate corrosion... no good!