[Hayk90]

I’m getting a low fluid warning even with a full tank of washer fluid.

Took out the reservoir and found a ton of RainX orange sludge all over the bottom half of the tank and inside the filler pipe. Both filters were clogged.

Surprisingly, the sensor is not submerged in fluid but instead sitting inside a separate dry cavity. I’m curious how the residue inside the tank may be impacting its ability to measure fluid and what I can do to test its operation.

Is there a resistance test I can perform and what are the acceptable values? Wiring looked intact but I wanna rule out the sensor before I go to other options.

[mecheng77]

I can't remember but does it use a float, and if so is the float sticking.
I know my Volvo uses a float.

[nsjames]

Originally Posted by mecheng77

I can't remember but does it use a float, and if so is the float sticking.
I know my Volvo uses a float.

I had mine out recently and it's a segmented device that appeared to sense the fluid level by measuring conductivity.

I'd clean the potentially non conductive slime from it and see if it works again.

otherwise yu'd have to try and ohm it out in liquid I imagine.

I was there fixing leaks, so aside from taking it out I didn't investigate too much.

[BSM n54iS]

Just empty it out, you don't need no stinkin' washer fluid

[mweisdorfer]

Originally Posted by Hayk90

I’m getting a low fluid warning even with a full tank of washer fluid.

Took out the reservoir and found a ton of RainX orange sludge all over the bottom half of the tank and inside the filler pipe. Both filters were clogged.

Surprisingly, the sensor is not submerged in fluid but instead sitting inside a separate dry cavity. I’m curious how the residue inside the tank may be impacting its ability to measure fluid and what I can do to test its operation.

Is there a resistance test I can perform and what are the acceptable values? Wiring looked intact but I wanna rule out the sensor before I go to other options.

I had the same problem. I even replaced the sensor with no luck. It's a closed-loop, the wires would need to be joined together to remove the fault from appearing. Nothing coding wise can be done.

[Hayk90]

Originally Posted by mecheng77

I can't remember but does it use a float, and if so is the float sticking.
I know my Volvo uses a float.

I believe most cars use a float but this one is different. I'm not sure how it works but I believe it senses a magnet inside the tank.
The actual sensor is just two pieces of metal with a resistor or something like that in between.

https://standexelectronics.com/appli...vel-detection/

Originally Posted by nsjames

I had mine out recently and it's a segmented device that appeared to sense the fluid level by measuring conductivity.

I'd clean the potentially non conductive slime from it and see if it works again.

otherwise yu'd have to try and ohm it out in liquid I imagine.

I was there fixing leaks, so aside from taking it out I didn't investigate too much.

So the sensor is complete dry and isolated from the liquid. Maybe BMW used different sensors throughout the E9x years?
The slime is on the inside of the tank above and around where the sensor lives.

Originally Posted by BdSM n54iS

Just empty it out, you don't need no stinkin' washer fluid

Originally Posted by mweisdorfer

I had the same problem. I even replaced the sensor with no luck. It's a closed-loop, the wires would need to be joined together to remove the fault from appearing. Nothing coding wise can be done.

I'm really trying to avoid doing that. I would like to figure out what the issue is as I'm being told the sensor used to work normally when the car was parked a few years ago. I can test the wiring, but I don't think it's broken.


This is how the sensor is inside its cavity. Again, it's NOT inside the liquid.



With the plastic tube removed.

[Hayk90]

Okay I’m pretty sure I found the problem.

There is a rectangular float that’s inside the tank. It rides on a stem around the cavity where the sensor lives. That float is currently stuck in the low position and not moving. The orange goo is not letting it go.

I’m trying hot water and a long stick to try to get it to move.

Worst case scenario I’m gonna replace the tank with a used one. But I’m 99% sure that’s my problem.

[nsjames]

use alcohol.

the stuff that came from the washer fluid was originally suspended in it. .

[Hayk90]

Originally Posted by nsjames

use alcohol.

the stuff that came from the washer fluid was originally suspended in it. .

That’s funny you say that, I just tried to pour some alcohol in there as a last resort and it seems to be working. I may need to seal up the whole container somehow and try to leave it in there for a while.

[Hayk90]

Fixed! Got the float moving just enough to remove the warning light. Everything works, no leaks.

I decided to order a salvage replacement tank just to completely forget about this problem. It comes with pumps, the sensor, and the wiring harness, all for $40. So I’ll have spares as a backup.

I thought about the issue with someone else and we came up with this theory.

The car had a bad lid on the filler neck which kept it open. The car sat for two years outside. Alcohol inside the RainX fluid evaporated and the additive package turned into goo that stuck to everything inside. The first repair shop I took the car to must have added some fluid to get the light to go out and I think it worked on my first drive. Then it sat again for about 3 months while I worked on everything else. Fluid evaporated again but now it got worse to a point that it wouldn’t budge anymore. So adding alcohol and doing the thorough cleaning got it unstuck.

[y2k_o__o]

Originally Posted by nsjames

use alcohol.

the stuff that came from the washer fluid was originally suspended in it. .

my m3 also has this problem.
tested and confirmed wiring is OK using multimeter, and replaced level sensor, and still getting the warning light.

The green supertech washer fluid already contains methy alcohol in there, i assume the alcohol isn't concentrate enough to remove the goo ?

[nsjames]

Originally Posted by y2k_o__o

my m3 also has this problem.
tested and confirmed wiring is OK using multimeter, and replaced level sensor, and still getting the warning light.

The green supertech washer fluid already contains methy alcohol in there, i assume the alcohol isn't concentrate enough to remove the goo ?

possibly.

washer fluid is a pretty low concentration.
some straight 90% IPA probably dissolve all the nasty.

coincidentally I've developed a new leak from the pump, so I'll be in there this weekend again and I'll have a look at how all that works.