S-Class (W221) 2007-2013: S 320 CDI, S 350, S 450, S 500, S 550, S 420 CDI, S 600

Windshield washer fluid low warning but reservoir is full

Old Mar 4, 2015 | 12:57 PM
  #1  
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Windshield washer fluid low warning but reservoir is full

Hi Everyone,

So lately the warning light that says windshield washer fluid low has been on when I know I just filled up the reservoir and I thought it was because the sensor might have gone bad. But I also read a TSB that the conductivity of the fluid can also be the problem. The sensor is just an electrical switch whose circuit closes when theres a conducting solution. So deionized water will cause a false reading. I started using Rain X and was wondering if anyone knows of Rain X could contaminate the sensor somehow or should not be used. I switched back to regular fluid and it hasn't turned off yet but maybe it takes a bit? Before I go to the dealer and cough up money I was wondering if anyone knows if theres a trick to getting it to work again. If not there might be a diy on how to remove your reservoir/change your level sensor and possibly wiper fluid motor
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Old Mar 4, 2015 | 03:06 PM
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Fluid level sensor is part 2218209110

Reservoir
http://www.google.com/url?sa=t&rct=j...,d.eXY&cad=rja
W/ABC
http://workshop-manuals.com/mercedes...washer_system/ + next page

Pump
http://workshop-manuals.com/mercedes...ce_and_repair/
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Old Mar 5, 2015 | 11:32 PM
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Thnx again for the info! A friend of mine who's a mercedes tech told me to try cleaning the sensor first because it may just have some depositing on it and if it doesnt work then get a new one. I definitely need a new pump though the jets are weak and little fluid actually gets onto the windshield
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Old Mar 8, 2015 | 04:25 PM
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Just curious, is there an $80 per gallon washer fluid they "recommend" we use to prevent issues with the sensor ???
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Old Mar 8, 2015 | 06:12 PM
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MB Summerfit part 001986807117, Winterfit 002986147109
Attached Thumbnails Windshield washer fluid low warning but reservoir is full-capturea.jpg  
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Old Mar 8, 2015 | 10:01 PM
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The Walmart special works well lol. Don't sweat the washer fluid. Just make sure you adjust the jets so no fluid puddles on the hood/ a-pillars. Some fluids will stain the paint if left for long periods of time- holds especially true for SUVs and rearwiper jet that might puddle on rear bumper.

Last edited by alx; Mar 8, 2015 at 10:09 PM.
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Old Mar 8, 2015 | 10:57 PM
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Originally Posted by alx
The Walmart special works well lol. Don't sweat the washer fluid. Just make sure you adjust the jets so no fluid puddles on the hood/ a-pillars. Some fluids will stain the paint if left for long periods of time- holds especially true for SUVs and rearwiper jet that might puddle on rear bumper.
The walmart special works for me
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Old Mar 8, 2015 | 11:28 PM
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Whatever happened to using a simple mechanical float?????
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Old Mar 9, 2015 | 12:19 PM
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Google 'Rain-X washer fluid sensor problem' or similar and you will find all kinds of documented problems with it, especially their new formula. Especially bad with VW sensors but many brands report issues. Best to avoid it.
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Old Mar 9, 2015 | 12:22 PM
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This is ridiculous. I've used store bought basic wash fluid all my life and never had to worry. It's blue, and doesn't freeze.
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Old Mar 9, 2015 | 01:08 PM
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Wow i got some pics to show. Rain x straight gunked up the whole system. Yeah i can confirm DO NOT use rain x in your reservoir. It contaminated everything. Cleaning it with some brakleen. Gonna do a write up by later today
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Old Mar 9, 2015 | 01:12 PM
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Must be why the jets are weak too
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Old Mar 9, 2015 | 02:38 PM
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Ok problem solved. The sensor was heavily coated in rain x residue.

Tools needed:

Flathead screw driver

10mm socket/wratchet

Tiny hands

A beer

A lot of swearing

Make sure the reservoir is empty or you'll have a mess everywhere. Pop the hood and locate the 10mm nut holding the reservoir


Next remove the engine cover and air duct on the reservoir side


Next unclip the heat exchanger hoses and disconnect and move them out of the way.... DO NOT unhook the rubber hoses from the aluminum or you will drain tour engine coolant. The engine coolant runs through these to warm the fluid.






Last edited by Nickthegreek; Mar 9, 2015 at 05:10 PM.
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Old Mar 9, 2015 | 02:45 PM
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Next remove the black lid that covers the heat exchanger hoses and move it out of the way


Now remove the heat exchanger. You have to finagle it out without disturbing the hoses too much. Its a PITA but itll come out.




Heat exchanger





Heavily caked in rain x :/
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Old Mar 9, 2015 | 03:09 PM
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Good work. Rainx to the windshield washer system is what is slick 50 to the engine. Garbage resulting in sludge and malfunctions lol. It does wonders to the nozzle pump (impeller) too...
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Old Mar 9, 2015 | 04:08 PM
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Originally Posted by alx
Good work. Rainx to the windshield washer system is what is slick 50 to the engine. Garbage resulting in sludge and malfunctions lol. It does wonders to the nozzle pump (impeller) too...
Im contenplating whether or not to replace that too but iam going to try a trick to try and clean out the system using a detergent if not ill replace the hoses and impeller
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Old Mar 9, 2015 | 04:20 PM
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Next start pulling up on the reservoir. There will be a plastic emissions hose and the hose that connects to the washer fluid pump that will impede it coming out move the emissions hose over a bit then remove the washer hose. They really need to have made it longer so it can be taken out easier.



Pump hose is disconnected





Disconnected. Once you disconnect this hose the reservoir should start coming out
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Old Mar 9, 2015 | 04:27 PM
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Now disconnect the electrical connections of the two pumps and the sensor. I never knew that there were two pumps. If anyone knows what each pump is for let me know. To disconnect the connections on the pumps you have to press down on the plug but pry up on the tab and then youll hear a snap and it will come right off


Then the connector for the sensor will be different. Push down on the plug then push on the tab instead and it will come right off. Now you are left with this



The pumps were taken out. The pumps are easy to remove. There is just a spout that fits into a grommet/seal. The sensor is what is left on the reservoir





The pump
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Old Mar 9, 2015 | 04:32 PM
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Ok now we remove the sensor. The sensor is seated in ther good so youll need a flathead screwdriver to pry up on the edge just a bit. If the plastic starts to bend, ease ofd and go in another spot. It should slowly raise up a bit. Then once you can start wiggling it it should wiggle right out. Do not try to rotate it theres a locking tab that you may break






Locking tab. Pry on the edges where it is round
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Old Mar 9, 2015 | 04:37 PM
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Now remove the sensor. Mine was caked in rainx and had an orange layer of slime over it. I cleaned it with brakleen and it got it back to bormal



Before.





Before. It doesnt look like theres much on it but if you were to run your finger up and down the sensor it is a slippery slimy layer blocking conduction





After. No more slimy layer used brakleen and a paper towel
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Old Mar 9, 2015 | 04:43 PM
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I tried wiping out as much of the slime from the reservoir and heat exchanger as well. For the heat exchanger i used brakleen and got it as clean as possible. The reservoir had tons of caked on slime. I figured out a trick. Powdered Tide works as a mild abrasive and an emulsifier. I poured dry tide into the reservoir and scrubbed it and as i rinsed it it came right out with the water. Got it as perfect as i could






Nothing but orange slime
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Old Mar 9, 2015 | 04:49 PM
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Ok now time to put everything back
Pretty simple. Put the sensor back on.Put both pumps back on. One will have a hose the other wont.

Heres where it gets a little tricky. Put the reservoir back in place but not completely and leave some room for your hand so that you can attach the lower hose back onto the washer pump




If you have the hands of a 9 year old asian bky this should be no problem. Then tuck the tubing/ wiring under the radiator crossmember
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Old Mar 9, 2015 | 05:01 PM
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Ok now youre on the home stretch. Seat the reservoir and then put the heat exchanger back in. Itll take some finagling but itll go in pretty easy. There is a nozzle that fits into a dimple in the reservoir. Make sure this seats into it.



This nozzle goes into the dimple in the reservoir shown below.





The dimple at the bottom. Couldnt get the reservoir as clean as i wanted but itll have to do

Now seat it in and replace the cap and reclip the hoses. Then pour in the correct windshield washer fluid




Heat exchanger seated

Now check your instrument cluster.... and BOOM!



0 messages

And tell the dealer suck your kahones

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Old Mar 9, 2015 | 06:43 PM
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Nice write-up! I have a feeling that the cause of the build-up is the de-icing agent in the fluid. It's probably best to use wiper fluid that does not include a de-icing agent in it. There are several that use that agent, so be careful in the one you choose to use.
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Old Mar 9, 2015 | 06:48 PM
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Awesome write up Nick!
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