This happened to my 2013 3.6R a couple of weeks ago. These washer fluid sensors are infamous for failing after a decade or so. They are not sold separately, you must buy an entire reservoir assembly, and most of us decide it is not worth the money or the disassembly/installation hassle so we just disconnect the electrical connector to the sensor at the bottom of the reservoir in order to shut off the warning icon on the dashboard. That is exactly what I did and I am fine with it because I always visually check the fluid levels whenever I open the hood anyway.

 

This happened on my 2020 Outback and for whatever reason it fixed itself after several months. Don't know the root cause in my instance - not sure if mine has a float or electrodes or how it determines low washer fluid.

 

I had the problem a couple years ago on my 2014. After finding out the only fix was to replace the tank I tried taking a long plastic zip tie, the kind used on heating ducts, inserted it into the tank and agitated the contents of the washer tank all the way to the bottom. Light went out and as near as I can tell it has functioned properly since then. (Maybe the agitation cleared some blockage/sluge in the sensor. ??)

I hope I didn't just jinx it, but I still have the 18 inch zip tie with my car cleaning stuff just in case.

I think there are some discussions where folks have disconnected the sensor, and one where a resistor was placed in the discontected lines to fool the ECU. In those cases the warning of low washer fluid is when the fluid stops spraying on the windshield.

 

Just unplug the sensor. The dash light and the "I" light will turn off.

Here's a recent thread that covers all the bases.

Windshield Washer Fluid Sensor Location ?

2013 Outback 3.6R My dashboard displays a "Low Windshield Washer Fluid" message upon ignition start-up, but my washer fluid reservoir is full almost to the brim. Where is the sensor and how is it accessed on these 3.6R models? The filler tube runs down and underneath the battery. Sure hope I...

www.subaruoutback.org

 

The light has come on twice in my 12 Legacy (the fluid is usually pretty close to full) - if you undo the plastic fittings and pull down the front of the drivers side mudguard, the bottom of the reservoir and the sensor are right there - each time I thumped the bottom of the reservoir a few times and unmated/remated the connector and the light went out. I figure the float is getting stuck or something.

Good to know that unplugging the sensor turns off the light... that might be a more appealing solution than spending $80 on a replacement when the sensor fails for good!

 

Thanks for all the ideas. I drained my wiper fluid by driving around and using it then took a kettle of hot water, roughly 150 degrees and poured that in there. Then I drove around my neighborhood weaving back and forth ti agitate the water. The light went off within 200 feet. I sprayed all the hot water, the light came back on as expected and repeated the hot water process. It went off again so this work for me.

 

you got a old thread here. ...and 150 F seems ...OK but hotter than that I would think it would be bad,.. glad it worked for you,...I would have considered some degreaser in the mix.

what kind of sub-bar-ru do you have?