Re:

["Douglas Hurst Quebbeman" <dougq@iglou.com>]

> My "check cooling system" icon appears _some_ of the time.  The coolant
> level is *not* low.  It is *not* hot.  (I need a new thermostat but that's
> a different story.)
> 
> What else should I check for the cause of this false alarm?  A faulty temp
> sensor?  Where?

I had the same problem, and deduced it to be the overflow recovery 
unit's coolant level sensor. Like you, I could be certain that the 
engine was not overheating and could visually verify the coolant 
level as OK. I dosconnected the sensor, and the alarm went away.

I still don't know if the problem is in the sensor itself, or the 
wiring leading to it.

hth,
doug q    (finally getting to enjoy a quattro in its best element!)
 
--
-Douglas Hurst Quebbeman (dougq@iglou.com)            [Call me "Doug"]
    QuattroClub USA# 4536              Audi International # 100024
       74 100LS Auto, 77 100LS Auto, 84 Coupe GT, 86 5Kcstq   
"The large print giveth, and the small print taketh away."  -Tom Waits