Check Engine light - Slight water leak

[Teresa]

Hello,
 
I have a 1993 Audi 90S which I purchased 2 years ago.  The car has been
running great ever since I bought it and I haven't had much trouble
aside from normal wear and tear items.  This morning my check engine
light came on while I was stopped at a stop light.  Upon reaching my
destination and leaving about 30 minutes later the light didn't come on
when the car was started.  It did however come on again when I was
stopped at another light(each time I was stopped about 45 seconds before
the light came on).  The car is still running great, no loss of power, a
smooth idle, no strange noises, etc.  I checked all fluid levels and
they're within the normal range.  I did notice after being parked for a
bit(15 minutes or so)and driving away that there was some water under
the car.  The AC was not running & the fluid was water(pretty sure
anyway, I felt it and it felt like water and was completely clear in
color).  
 
My mechanic won't be in until tomorrow and I don't know much about cars,
so I'm wondering if anyone has any ideas on what might be wrong.  Could
it be my water pump?  I had my timing belt replaced a year and 4 months
ago but not the water pump because the mechanic didn't have the part in
stock and wouldn't be able to get it until the next week(leaving me
without a vehicle that weekend).  If it is the pump should I avoid
driving until I can get it in to the garage(which will probably take a
week or so to get an appointment)?  
 
I took the plastic cover off my engine area and noticed a bit of "gunk"
on some of the hoses and saw a spot of coolant further down.  One hose
has some tape around it(looks like electrical tape)and it's one of the
hoses with the "gunk".  I checked for signs of coolant in my oil and oil
in the coolant and saw no signs of cross contamination.  
 
Does anyone have any ideas or advice?
 
Many thanks,
 
Floyd