So switching to the cheapo Walmart blue stuff fixed my leaky rear nozzle for what its worth
I had the same problem with the "Top Washer Fluid" light being consistently on after I used Rain-X winter washer antifreeze fluid.
My dealer wanted $300 to fix the problem - they explained the inexpensive sensor needed to be replaced or cleaned, but the labor costs account for most of the $300 as they would have to remove the grill, bumper cover, headlamp and fog lamp.
I was able to fix the problem myself for less than $10 and I did not need to remove any body parts.
I used the washer pump to drain the reservoir, splashing the fluid out onto the rear window. It didn't take that long, probably five minutes.
Then I added a full 28 oz bottle of CLR to the tank and then topped the tank off with regular water.
I let the solution sit in the tank for 48 hours then again spritzed it out onto the rear window. (I used a garden hose to wash off the back of the car - I don't know if diluted CLR will harm the paint or finish but I didn't want to take a chance.)
Then I refilled the washer tank with approved cheap-o blue washer fluid and voila! Problem solved.
:w00t:
Good luck,
James