Samsung Waterwall Dishwasher (DW80J7550US and others): How to fix Waterwall Problems, C7/E7 Error Code, Dirty Dishes on Bottom Rack

notronjeremy

Premium Member
Joined
Sep 15, 2019
Messages
2
Location
Minnesota
Model Number
DW80J7550US
Brand
Samsung
Age
1-5 years
I've wasted more time than I'd like to admit troubleshooting this problem, but in doing so have developed a pretty good sense of how to attack it so thought I would share my findings with others.

Here are the things you might notice if you are having a problem with the functionality of the Waterwall bar:
  • If you run a pot through on the top rack it comes out clean, but running the same pot through on the lower rack it comes out nearly as dirty as when it went in (as if no water was shot up into them from below).
  • You either see error code C7/E7 or can recall it by holding the Normal and Lower buttons on the dishwasher for 7 seconds (this brings up the last error code captured on the display).
  • You hear three dings about 20-30 seconds after starting the dishwasher.
If you're having these problems on a brand new dishwasher there are a list of things that could have went wrong during assembly, but I'm going to skip those since Samsung support should be capable of guiding you through those. If you're having these problems on a dishwasher that previously worked properly then this guide is for you.

How the Waterwall system is supposed to work:
When you start any cycle on the dishwasher the very first thing it does is verifies that the waterwall arm is functioning as it should and is free of obstructions by driving it all the way to the front of the dishwasher, all the way to the back (at which point a magnet in the waterwall arm is detected by a sensor under the floor of the dishwasher), and then repeats that cycle one more time. If this cycle fails for some reason the dishwasher registers error code C7 or E7 and disables the use of the waterwall arm for the whole wash cycle.

If this happens you will still get some cleaning on the lower rack since some water will still shoot out of the lower jets towards the waterwall, but since it's stationary it will only hit a small area on the lower rack above where the waterwall bar sits. In this case your problems could be that the waterwall vane motor is weak, the sensor located next to the motor (that detects the magnet in the waterwall arm), or the magnet in the waterwall arm itself has become too weak to set off the sensor. In fact, it could be more than one of the.

How to diagnose which part is to blame:
  1. Take a flathead screwdriver or a butter knife and stick it into the slot in the dishwasher door where the latch normally sits (this is how the dishwasher detects when the door is closed).
  2. Select a cycle on the dishwasher, press the Start button on the dishwasher, and then apply pressure against the screwdriver or butter knife in such a way as to activate the door closed sensor. You'll know you got this right when the blue light on the front of the door lights up and the wash time disappears from the display on the top of the door. Hold it steady as you watch the dishwasher operate.
  3. As soon as the cycle starts the waterwall arm should behave as described above. If it doesn't move at all then the most likely problem is the waterwall vane motor is broken, although it's worth running your fingers under the bar it slides on top of, feeling the rubber belt down there and verifying that isn't moving either, even when you apply some tension to it. If the waterwall does move, but it's choppy or weak (verify this by providing some minor resistance to it with your hand and see if stops easily or requires a small degree of effort to stop it) then the motor or the belt are the likely culprits here with my money on the motor.
  4. If the waterwall arm is moving properly verify that when it reaches the rear of the dishwasher that the dishwasher detects it and stops trying to pull it back. If it keeps trying to pull it back, even after reaching the home position for a while then the problem is most likely either the magnet inside of the waterwall bar (which can degrade over time) or the sensor that detects the magnet). A good way to figure out which is the culprit here is to get a rare-earth magnet and see if that is enough to set off the sensor or not (causing the bar to stop retracting towards the back of the unit). If you examine the bottom of the waterwall bar (it easily snaps up and off of the small plastic guide underneath it) you should see a single screw towards the center, which is where the magnet resides. You could set the test magnet onto this magnet (should stick together simply through magnetic force) as a means of completing this testing step. If even the strong/test magnet doesn't cause the waterwall bar to stop retracting after reaching the home position then that suggests a faulty sensor. If the motor is weak or broken you could also infer this result based on listening it and whether the motor stops making noise, which would indicate that the dishwasher believes it got where it wants it to go or (if 20+ seconds has passed) the dishwasher gave up and timed out.
  5. Before 20 seconds pass from the time you started the cycle you should remove pressure from the knife/screwdriver so that the dishwasher thinks the door has been opened. This will avoid it reaching the point where it starts letting water flow into the dishwasher. You may have to repeat this process a few times to test everything you need to test.
How to fix the waterwall mechanism based on what you now know:
If the problem is that the magnet in the waterwall arm is too weak to set off the detector, but your rare earth/test magnet was strong enough to set it off then you got really lucky. You can simply remove the old magnet and epoxy the replacement magnet in its place (or if the replacement is small enough you might not even need to remove the old one). There's a video on Youtube uploaded by "HonestDad" that covers this fix fairly well so hunt that down if you need more detailed guidance.

If the problem is that the sensor needs to be replaced (but the motor is still good) you can probably hunt down a replacement for ~$30 and replace it. In this case you have to pull the dishwasher out, lay it on its back, and remove the bottom access panel (just one screw then snap off plastic cover). You will be greeted with three black rubber hoses. If you look behind the hoses you'll see a small motor and mounted to the same piece of plastic as the motor you'll see a small just under 1"x1" square piece of plastic that is the detector. You may need to temporarily move the black hoses out of the way to access it if you have large hands, but that's pretty easy to do by using plyers to squeeze the metal braces that attach them and then pulling them off of the plastic tubes they're attached temporarily. Obviously don't forget to reattach them when you're done. Also note that in order to finish replacing the sensor you'll have to tip the dishwasher back up, remove the rear access panel on the bottom rear of the unit (two screws and lift off) to gain access to where the sensor attaches and replace the plug on the new one there. If you're unclear on how to complete this replacement you may want to read the next section and find the recommended videos since the motor and the sensor are in close proximity and knowing how to get to the motor will help you know how to get to the sensor.

If the problem is the motor (like it was for me) then you have a couple different options. First read the last paragraph where I described how to get to the sensor and realize that this is also how you gain access to the motor. It is attached to the assembly by two screws that are in tight quarters. You can either try your luck removing just the motor and replacing it (which is arguably safer since you're disassembling less stuff and less likely to screw up reassembly and create a small leak when you didn't tighten something properly (I won't get into why I bring this up here, but it is a real concern), or you can remove the entire assembly the motor is attached to, which is what I chose to do because I was following a Youtube video and it didn't occur to me the recommended method was more work. I'll cover both methods here:
 

notronjeremy

Premium Member
Joined
Sep 15, 2019
Messages
2
Location
Minnesota
Method 1:
If you want to remove just the motor you need to unscrew the two screws holding it in place. Since there are three rubber hoses blocking your way you will have to remove those first. I would do that by first going in through the rear access panel and using plyers to squeeze and lower the metal clips holding the hoses in place, then pulling the rubber hoses down and off of the plastic tubes they're attached to. While you're back there detach the 4-wire connector leading to the motor you'll soon be replacing. Then carefully lay the dishwasher flat on the back and go in through the access panel on the bottom of the unit. The three black hoses will be attached to three plastic tubes on this end as well. Remove the hoses from these tubes the same way you did on the other side and lay them aside, keeping track of which one goes with which tube. Not sure it's that critical you match them up perfectly, but each has been playing its part effectively up until now so no good reason to change them up. At this point you'll have better access to the motor and should be able to unscrew the two screws holding it in place. You should be able to just pull the old motor out and either repair it or swap in a replacement for it. Note that when inserting the replacement there's a good chance it won't align properly (you'll see the shaft has a slit removed to allow it to turn the mechanism it attaches to). To resolve this apply pressure to the motor to push its shaft into the hole, while having a helper move the waterwall along its path until it causes the shaft and the mechanism to line up and the motor slip in. Tighten the screws, reattach the rubber tubes (from both ends), snap the connector for the new motor into place, and you should be done with the replacement. See below for a discussion on replacement VS repair of the motor:

Method 2:
This is slightly more involved and how I ended up doing it based on a Youtube video I watched, but not horrible. Basically, instead of removing the motor from the plastic assembly it is attached to this method removes the entire plastic assembly from the dishwasher first and then you would replace/service the motor. Why would you want to do all that extra work when Method 1 should be sufficient? Economics are one consideration. If you've decided you want to replace the motor rather than repair it then a new motor will run you ~$100, while a replacement motor, sensor, and the plastic assembly they both attach to won't cost you that much more money and it's all put together for you for a more complete repair. But let's just get into it...
For this method you start by going in through the rear access panel. You first remove the rubber hoses from the plastic tubes as you would in method 1 and then you unscrew the plastic fasteners from where the tubes extend up into the body of the dishwasher. This is easily done by twisting them part of a turn to get them to release, but the direction you turn them is the opposite you would expect to free them.
With the hoses detached from the tubes you'll now be able to reach the motor and note that the plastic assembly its connected to also has a plastic fastener ring, only much larger and on much tighter. This one should loosen counter-clockwise, unlike the smaller ones. You may be able to get it off by pushing a flathead screwdriver against the grooves around the edges or perhaps you have a fancy tool that lets you twist such objects. Once that is removed/free be sure to unsnap both the wiring connection to both the motor and the sensor.
Now go inside of the dishwasher, remove the trays, use a small flathead screwdriver to snap a pair of rubber covers off of the top of the plastic assembly with the waterwall jets in the rear of the unit. These can be tricky to see at first, but if you look closely you'll see them. Once they're snapped off unscrew the two screws underneath. In lifting up the piece you just unscrewed you'll noticed that it's attached to a metal guide that extends to the front of the dishwasher and at that point is only attached by a rubber snap that is easy to pull it away from.
With that assembly out of the way you'll still have a plastic tube extending up along the rear wall of the dishwasher, all the way to the top. This is held in place by small metal clips on the top and rear of the dishwasher that you can push to the side with a screwdriver, while pulling the plastic tube away from them, finally lifting it out of the unit.
With that piece removed the last remaining hunk of plastic in the rear of the dishwasher is the assembly the motor and sensor are attached to and will lift right out.
When reassembling you can mostly just reverse these steps, but I'd suggest saving the steps that involve reattaching stuff to the inside of the washing area of the dishwasher for last, securing the plastic assembly with the motor on it and locking it in place first. It's also important that the plastic fasteners are reattached snugly. The smaller three shouldn't need to be tightened more than by hand, but for the larger one that fits around the motor you're going to want to give that one a little more force, otherwise it will pop right off during dishwasher operation, you'll get an LC (leak) error, and you'll find yourself having to go in through the bottom access panel again to fix that. My suggestion for tightening the larger of the plastic fasteners is to attempt it through the bottom access panel (removing rubber hoses if necessary for leverage). Shine a flashlight at it and ensure that the plastic locks are turned far enough clockwise that it's going to stay in place and won't pop back off with minimal force.

Repair VS Replace Motor Considerations:
There's a Youtube video posted by Matt Rampone in which he walks you through the process of repairing the Waterwall Vane motor: It's a simple AC motor, but designed with a very weak piece of plastic in it that's likely to break over time, causing the motor to lose strength or fail completely. It's not clear whether this design flaw has been corrected so if you replace the motor it's not unreasonable to imagine the new one could fail again in another few years. If you don't mind tearing your dishwasher apart every few years and swapping out motors then simply swapping in a new motor is fine; however, Matt's repair suggestion should lead to a more durable, longer-lasting motor if you're not scared of attempting what he does. And if you screw up along the way, ruining your already-broken motor further it's not like you're out anything more than you would have had you just replaced it. I'm not going to go through his full repair procedure here, but in a nutshell, he disassembles the motor, uses epoxy to repair the weak piece of plastic, and also uses epoxy to permanently affix it to the permanent magnet inside of the motor, which should greatly reduce the chance of it failing in the future. The only real risk I can see to his method would be if it made the motor too strong, to the point where a future failed sensor/magnet in your dishwasher caused it to tear the belt when if it continued to drive it past its end-point. The other warning I'll give is that Matt follows what I've called Method 2 of removing the motor from the dishwasher, which does introduce the minor leak/error code LC risk I described earlier.

I personally tried to follow along with his example, somehow reversed the polarity of the motor due to not taking my time, tried to disassemble it again to resolve that, ended up stripping a screw hole in the plastic assembly it attaches to, and opted to replace the full assembly with motor and sensor (method 2 above) instead of attempting further repair on the motor.

Final thoughts:
What a poorly designed and documented feature by Samsung. The Waterwall concept sounds neat, but it's unfortunate that there are three separate components (that all would be expected to degrade over time) and any one of them failing make the bottom row and utensil racks of the dishwater largely useless. Then to further frustrate matters, if the sensor or magnet fail, both presumably would put more wear and tear on the motor (when it doesn't stop at the home position), causing it to fail sooner too. If you're having a problem with waterwall operation it might not be the worst idea to just replace all 3 pieces at the same time, while you're already working on it anyway.
 
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