Where did you put the fluid?
Was it completely empty before?
The pump needs to prime, keep the sprayer pressed for a couple of minutes

 

Mercedes Owner's manuals usually note not to use distilled/deionized water in there, or the float level sensor may be damaged....

 

I put the fluid in the wiper fluid resivoir as indicated by the blue cap with the wiper fluid symbol on the top.

I used Rain X fluid to fill the resivoir and I am not sure if it was completely empty. I tried holding it down for a couple of minutes and nothing changed.

 

Be careful to read what is mixed in. Some Prestone fluid says it is mixed with de-ionized water for better cleaning. I'm guessing that the sensor went bad, and everything else is okay.

 

I know living in AZ this may be a stupid question, but do have the heated washer system?

 

So I've only owned this car for a month and I don't believe it has a heated system. How would I check that?

*Update* on my way home from the store I decided to try the system and it worked. I tried every five minutes for about 30 minutes and it seems to be working again. However I'm curious if this is a sign of future failure or if the resivoir was just empty and the pump needed to be primed.

 

Also the system is still saying top up wiper fluid. I have put two bottles worth in there. Anyone know how large the tank is?

 

If I recall it is almost 8 quarts. So two bottles should have turned the light off.