Why is my window wiper fluid warning light come on all the time

First thing I do is check for cracks in the tank and tubing. Thankfully, the window wiper fluid can't mix in the engine like radiator coolant can, so it's contained. Check for cracks in the tank, as well as damaged/loose/cracked tubing. It might be as simple as a new tank or a new piece of tubing. That said, if the tubing and tank appear to intact and there is no leak in sight, it might be a sensor issue.

This code will not appear on your typical OBD2 reader, as it is usually a vendor-proprietary B or C code - only the P codes are openly available due to emissions-related checks. Either buy an all-system scanner, or have it scanned and ask for a report and pay for ~1 hour of labor. Once you have the codes, you can start looking at it. But chances are it's a bad sensor. That said, without the exact year, we can't locate it, but search for "Nissan Armada wiper fluid sensor". If you have one in 2 separate places, I would change both IF both are less than $20 to make sure it's fixed for good. The Nissan P/N is 28911-1E400, and yours only has one sensor.