MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
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In this guide (7 sections)
Are you experiencing problems with the windshield washer on your Mercedes-Benz? This article will help you troubleshoot problems such as windshield fluid not coming out or the windshield washer fluid pump not working.  It is important to accurately diagnose the problem before you rush to replace the windshield washer fluid pump.
Symptoms
- Windshield Washer Fluid Stopped coming out
- E-Class windshield washer fluid leak
- C-Class Windshield washer not working
- Mercedes windshield washer hose disconnected
- Washer fluid leaks on the ground
- Mercedes windshield wiper fluid is not working
- Mercedes washer jets are not working
What Usually Causes It
The fix for windshield washer fluid problems can vary depending on the issue. We have seen many cases where the problem is simply a disconnected washer fluid line, which can be very easily fixed at home.
Top Windshield washer fluid problems.
- Disconnected Washer Fluid Line / Hose (See fix below.)
- Mercedes washer fluid reservoir leak
- Defective Mercedes Windshield Fluid Pump
- Burned-out fuse
Open the bonnet, have someone pull the washer stalk with the key in position 2, and listen at the reservoir.
- You hear the pump run and nothing reaches the glass. The electrics are fine. The fluid is going somewhere else: a hose popped off its spigot, a blocked or misaimed nozzle, or a split line. Follow section 2 below.
- Silence. The pump is not being commanded or not being fed. Fuse, stalk switch, wiring, the pump itself, or on later cars a failed output in the front SAM. Follow section 1 below.
- You hear the pump and the level drops fast with nothing on the windscreen. You are pumping fluid onto the ground. Look for a wet trail under the car and a split in the reservoir or a hose.
That one test is worth doing before you buy anything, because a pump that hums is a pump that works, and the most common fix in this whole article is pushing a hose back onto a spigot for nothing.
Troubleshooting Mercedes Windshield Washer Problems
To diagnose windshield washer fluid problems, you must have a digital multimeter. The Mastech MS8268 MS8261 Series Digital AC/DC Auto/Manual Range Digital Multimeter is what we use in this tutorial, but you can use any digital multimeter that you like.
1. The Pump Does Not Run at All
- Check Pump Operation
Turn the key to the ON position and press the windshield washer fluid switch. Do you hear the windshield pump turn on? As you perform this test, make sure to have the engine off and the key in position II, or you will not be able to hear the pump turn on and off.
- Check Fuses
If the pump does not work, you should check the fuses next. The fuse for the windshield fluid is on the side of the dashboard or fuse box in the engine bay. In some models, it could also be in the fuse box under the rear seat. Find the fuse that belongs to the windshield washer fluid motor. Pull it out and make sure it is not burned out.
- Check the power to the windshield washer pump.
Use a digital multimeter to check whether power goes to the windshield pump.
You need to set your multimeter to measure DC in the 20-volt mode. If you need a multimeter tool, there are several inexpensive digital multimeters listed on Amazon’s Best Selling Digital Multimeter List. When you press the windshield washer switch on the steering column, you should see a reading of 12 volts.
- Test windshield washer pump.
If there is power at the plug but the windshield washer pump does not work, the next step is to test the pump (motor). You can feel 12 volts to the pump and try running it for a few seconds. - Replace the windshield washer pump.
If you conclude the washer pump is defective, you can replace it with a new one. Usually, the pumps are easy to replace. The hardest part is getting to the pump itself, as, in many cases, you may need to remove body parts such as a front bumper, a fender, or the wheel lining. New replacement windshield washer pump can be purchased on Amazon. If you would rather save even more money, you can purchase a washer pumps on Amazon.
You need to set your multimeter to measure DC in the 20-volt mode. If you need a multimeter tool, there are several inexpensive digital multimeters listed on Amazon’s 
2. The Pump Runs but Nothing Reaches the Glass
One very common problem that we see frequently is disconnected washer fluid lines. If the washer fluid line gets disconnected, you may experience no washer fluid spraying on your windshield or notice very little washer fluid spraying on the windshield. When this is the issue, the windshield washer fluid falls on the ground. Follow the steps below to learn how we fixed a similar problem using only Multi-Purpose Cable Ties.
- Inspect for leaks at the reservoir.
- Inspect the windshield washer fluid lines for leaks
How to fix a leak on the Mercedes windshield washer fluid line
- First, you should make sure the washer fluid pump runs when you press the windshield sprayer switch. In most cases, the pump works, but no water gets sprayed on the windscreen.
- Locate the fluid leak. In our case, we had a major water leak by the hood near the nozzle area.
- Â There are tabs that you need to release; however, in some cases, there will be few screws that need to be removed.
- Open the hood and remove the plastic cover from under the hood.Â
- Inspect the hoses on the windshield washer nozzle. In this case, one of them was disconnected.
- Press the hose back in place and use cable ties to secure it, so it doesn’t come out in the future.
- Test to make sure that water is spraying on the windshield properly.
The single most common reason a Mercedes washer reservoir splits is water left in it over a freeze. Water expands as it freezes and the thinnest part of the system gives way, which is usually the pump housing or the seam of the tank. A tank that only leaks in winter and seems fine in summer has already cracked.
Do not use household or engine antifreeze to protect it. Ethylene glycol attacks the paint and the rubber in the nozzles and hoses, and it is not what the system is designed for. Use a proper winter rated washer fluid or concentrate rated below the coldest temperature you actually see. Plain water in summer is also a bad idea, because it grows algae that blocks the nozzles.
If the tank is already cracked, a sealant or epoxy repair on polyethylene will not hold. The plastic is designed not to bond. Replace it.
A refill message with a full tank. That is the level sensor float sticking or its circuit, not the pump. The washers will usually still work.
Headlamp washers that seem dead. On cars fitted with them, they only fire with the headlights on, and only on the first wash and then every few washes after that. Pulling the stalk repeatedly and getting nothing is normal behaviour, not a fault. Those cars also share one reservoir between two pumps, so a leak on the headlamp circuit empties the tank you fill for the windscreen.
Frequently Asked Questions
- Where can I buy a replacement reservoir?
- A new reservoir is on Amazon, and the part numbers below will match it to your chassis. Check the number on your old tank before ordering, since several chassis share a shape but not an outlet position.
- Where can I buy a Mercedes washer fluid reservoir cap?
- If you have lost the cap for the windshield bottle tank, you can purchase a replacement cap on Amazon.
Related Part Numbers
- W163 ML320 ML 430 Windshield Washer Fluid Reservoir –Â 1638601160
- Reservoir Tank Cap Lid  MERCEDES-BENZ Wiper Washer Fluid – 9068690072
- Â W210 E320 Windshield WASHER FLUID RESERVOIR Bottle –Â 210 869 12 20
- W124 Washer Fluid Reservoir Tank  E320 E420 E300 – 1248690720
- W140 Chassis Windshield Washer Fluid Tank pumps S420 S500 –Â 1408600260
- VDO Washer Fluid Reservoir – 246061009002D 0008692120 Mercedes MB
- W211 E350 E CLASS WINDSHIELD WASHER FLUID TANK BOTTLE – 2118600060Â 2118600160Â 2118603760
- W463 G500 G55 windshield washer fluid tank – 4638600060
- Mercedes GLK Washer Reservoir Tank Windshield Fluid –Â 2048690320 Â 204 869 03 20
- W221 S550 S-Class  – 2218600160
- W215 W220Â S500 S600 S430 CL500 CL600 S65 Washer Fluid Reservoir Windshield –Â 2208690020 / 220 869 00 20 / 89533025001 / 895 33025 001 / 220-869-00-20
- R230 Â 2003-2006 Mercedes Benz SL500 SL55 SL600 Â Convertible Windshield Washer Fluid Tank -A2308690020 2308690020 230 869 00 20
- R170 Â 01-04 MERCEDES SLK320 WINDSHIELD WASHER FLUID RESERVOIR –Â R170
- W203 MB C230 C240 C280 C32 AMG CLK320 CLK500 CLK55 Windshield Washer Fluid Reservoir  – 2038690020 203 860 01 60 2038600160  2001 2002 2003 2004 2005 01 02 03 04 05
- W208 Â 99-03 MERCEDES CLK430 CLK320 WINDSHIELD WASHER FLUID RESERVOIR TANK –Â 208 869 00 20 2088690020
When a Scan Tool Is Worth Reaching For
On most cars this is a mechanical and fuse level job, and a scan tool adds nothing. There are two cases where it does.
- On later models the washer pump is switched by the front SAM rather than by a simple relay, so the pump can be dead because a SAM output has failed rather than because the pump has. A scan will show a logged fault for that output instead of leaving you to replace a pump that was fine.
- A refill message that will not clear after you fill the tank is the level sensor circuit, and that is read as a fault code rather than found with a multimeter.
The YOUCANIC UCAN-II Pro reads every module on the car, including the SAM that drives the washer pump and the level sensor circuit, and it covers nearly everything XENTRY does apart from online VIN coding.
Related Reading
Mercedes Wiper Problems
When the wipers themselves stop, park wrongly, or run at one speed only.
Understanding the SAM Module
The module that switches the washer pump on later cars, and what a failed output looks like.
Which Washer Fluid to Use
What to put in the tank, and what will crack it over winter.
Winterizing a Mercedes
Protecting the washer system and the rest of the car before it sits.
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
