Miele Dishwasher Issues

[tomwasher81]

I am looking for some advice. I have a Miele G6860 sci Dishwasher (UK model). I purchased it in March 2019, and it's been running fine up until the last few months.

We've been noticing that things are not cleaning as well and it seems to be using too much water. Some days, the water level is at the rim of the doors. No float switches or emergency pump outs have been triggered, though.

According to its consumption in the Miele app and on the machine, in some cycles, its up to 26+ litres of water which seems a bit excessive. The manual states that none of the cycles uses more than 15l of water, so I'm not sure what is happening.

I've also monitored the Automatic cycle, which is supposed to be a prewash (if dirty enough), main wash, interim rinse and then a final rinse. For dishes that I wouldn't classify as dirty, it can take 4 hours to run.

It seems to go through rinses where it partially drains some water, then immediately refills and continues rinsing for hours.

I thought it might be a faulty water inlet valve letting too much water in, so I stuck a GoPro into film part of the cycle. The water is correctly shutting off, and no leaking is occurring.

I've taken all the arms out and checked they are clean and free of food debris. The filter is intact and clean. The non-return valve works fine, and the sump is clean and free of debris.

It's out of warranty, but about 6 months ago, Miele came out as the solenoid was very noisy and "vibrating", so we thought it was faulty, but they checked it over and gave it a clean bill of health. I also checked in service mode, and there are no error codes logged on it.

Has anybody had something like this before, or do you have any ideas about what might be going on? Slightly reluctant to pay Miele another £139 to come out and say nothing is wrong with it.

 

[henene4]

Mieles still use a pressure switch, last time I checked.

If the machine thinks the water level drops, it adds more water as part of load compensation.

The water counter obviously works correctly since you get a read out in the app.
Double the water volume means less detergent action, explaining the cleaning issues.

That can be just something blocking the pipe between sump and pressure switch, or the pressure switch itself being problematic in some way.

Haven't had one in my hands yet, but the drying unit is on the right, so I would vaguely guess on removing the left side panel and look for the part.

Alternatively, a broken none-return-valve could cause cleaning issues, but wouldn't explain the high water usage - and 26l is above the maximum the Auto cycle would just use without extraordinary reasons.

Edit:

So it DOES use a pressure switch, that is connected directly to the wash pump though from what appears to be the case.

 

[henene4]

If it's actually an SCi model...

... and not an SCVi model, acessing the service menu is as easy as ever (keep the start button held down, turn on machine, while start button flashes press it three times, keeping it held in on the third flash until flashing pattern changes and release).

Since it's a text capable machine, navigating the menu is very easy.
That menu stores any fault codes, even those that aren't displayed during or at the end of the cycle.

With an SCVi - fully integrated - model, you don't have a start button, so not sure how that would be done.

On my G7100, the "OK" button can start a cycle aswell, so that might work.
But really not sure there.

 

[tomwasher81]

Apologies, It's an SCVi machine with an OK button. I have been in service mode, and there are no fault codes. It lists F0000 in it - although I am assuming that means no fault code. I could be wrong.

Would the pressure switch cause the cycles to run longer? I wondered if the turbidity sensor was at fault, making it run for longer than required. I guess the test would be to run an empty cycle and see how long it takes.

The sensor cycle will often skip the prewash, and our dishes are not that dirty; they never sit for more than a day or 2.

Appreciate any advice!

 

[henene4]

Yes, F0000 means no error.

Higher water volume means longer heating times.
Also means the machine thinks the load is bigger than it is.

A broken optical sensor wouldn't change water levels. Optical readings don't change fill levels, only wash temps and water changes.
Because that's an analogue value the electronic checks aswell, any off limit sensing for the optical sensor would leave an error code.

And 26l is above what the max Auto cycle can use by itself.
Even at max load size sensing and maximum soil, it shouldn't get much higher than 15l to 20l.

The pressure switch used (if I got the correct picture) appears to have 2 connection terminals.

That would mean that switch has both the overflow and the operation switch build into one unit.

As long as the overflow dosen't trigger, when ever the water level drops below a certain level, the main level switch will "trigger".
The machine thinks something flipped over - a bowl, a cup - and keeps adding water.
Once the overflow triggers, it will kick in the drain pump until that de-triggers.

If the overflow triggers to often, or to long, an overflow error would be stored.

So, if the main switch is wonky - maybe even the connection - it could think that something lowered the wash level over and over again and keep adding water.

But since the overflow works correctly, it doesn't store any fault code.

 

[jerrod_six]

Henene4: Do you have a picture or schematic showing where the pressure switch is located?

Tomwasher18: How do you get into the service mode on your SCVI machine since it has the OK button?

Thanks to both of you.

 

[gizmo]

I am not at all familiar with Miele dishwashers, but here is a suggestion...

 

Fisher and Paykel dishwashers from 20 years ago or so used to have an unusual water measuring method. The computer monitored the current draw of the wash pump motor to determine if there is enough water. When water level is low, the machine is sucking air, which provided little drag on the motor so it spins freely and uses little current. As the water level rises, it starts to pump water, which has more drag and consumes more power. Initially, it draws a mix of water and air, this tends to "pulse" the pump motor, causing it to fluctuate the power consumption. Once the water level is high enough, no more air enters the water flow and it pumps water only, this stabilizes power consumption at a higher current and the computer senses this, and shuts off the water inlet.

 

The problem with these F&P dishwashers was, there is a small screen at the inlet to the pump. This slowly accumulates scraps of food and other blockages over time, restricting the water flow. Due to this blockage, the pump can't get an adequate supply of water, spins too easily (cavitates?) and the computer never senses the water level is high enough. The first symptom is high water levels, if this isn't noticed, then the machine eventually floods. The fix is easy - remove the main strainer, reach inside and remove/clean the tiny hidden strainer.

 

I would be investigating if the Miele has something similar going on. It is possible that it uses similar motor sensing for its main water inlet control, and only uses the pressure switch to trigger "over-fill" protection such as shutofff and pump out.

 

Remember, I don't know Miele dishwashers, it's just a suggestion.

 

[henene4]

Mieles do not monitor either motor for load sensing or drain sensing from my knowledge.
BSH machines do, they manage overflow by literally letting the water overflow into the bottom of the machine and triggering the float switch for leaking situations.

I found this German video. The machine appears to be either a G2XXX or a G4XXX machine, but the general setup should be more or less the same, except yours uses a variable speed wash pump that looks different, but is connected to the sump at the same point.



The part that should be compatible with your machine should be this one (don't quote me on that, though; better to call up Miele and ask them for the part number just to confirm)
https://www.firstchoice-cs.co.uk/miele/mie6996821

The picture attached is the entire was pump unit with the pressure switch attached.

 

[richnz]

The pump in the picture does sense load

The technical information document says

The MPPW circulation pump does not have a Hall sensor to measure speed of rotation. Instead of utilizing the Hall effect, the load is registered by monitoring the circulation pump current consumption as follows:
During the water intake block, a certain fixed basic quantity of water is taken into the machine. The load is sprayed with this water and some is thus retained on items in the machine. The less water that flows back into the sump, the larger the load because more water has been needed to wet the individual items. The pump then has less water to circulate and its mechanical load is reduced. By measuring current peaks, the control-power electronic (SLT) calculates the additional quantity of water that must be taken in to carry out the program.

These pumps seem to have paved the way for the current motors on dryers and washers. The BLPM motors. Sensorless field oriented control.

26 litres in a cycle is odd. My g6860scvi uses 11litres.

 

[henene4]

Oh, I didn't know that. Thanks for the info.

I still doubt though that the pump is the culprit.

That description makes it sound a lot like the BSH approach.
If the pump was to be the issue, it would have to continuously give only ever so slightly off values.
If they fail, they usually fail to the point no valid value can be determined leading to at least some kind of error being stored.

That wouldn't give you the issue of draining then immediately filling either in the rinses.

And that routine is probably only used during initial load sensing - later fills will probably just use the initial load sensing data again.

If it is the pump though, you're looking at a repair of around 500€ - probably the same in £.

 

[gizmo]

Rich's answer sounds like the same technology as the F&P I mentioned.

It is an easy thing to check - remove the main filter/strainer, look inside for any inner/"hidden" second level strainer that might be blocked with food waste.

 

Pressure switches in dishwashers tend to be less reliable than the same device used in washing machines, as food soil is messy and can block the air passages, making the pressure measurement inaccurate. That is why load sensing is used in more sophisticated machines, with the pressure switch just a "second line of defense" against over-filling. The float switch (flood switch) would be the last chance, third line of defense, when the first two technologies have failed and the machine has actually started to flood. (also for hose failure, which floods under the dishwasher, not the wash chamber.)

 

The other advantage of motor load sensing to determine water level is that it ensures that the absolute minimum water is used for any wash load - just enough to prevent the pump pulling in air. If a dish inverts in the wash and suddenly retains a quantity of water, this will be detected and more water added to compensate. Pressure switches just aren't that accurate. This means less water used and less water heated, both important for energy star ratings in many countries.

 

Again, I'm not familiar with the Miele so I am not being adamant about this, but I would certainly check for any blockage that is restricting water flow to the wash pump, as it is a very easy and cost-free thing to check.

 

[gizmo]

Hi Henrik

 

My suggestion isn't for a pump failure, it is for a partial blockage of the water passages. This reduced flow changes the current draw of the motor which causes the computer to mis-interpret the data and continue to fill, because it has not sensed the motor current it expects when the pump is moving the correct amount of water.

 

My theory... (which may be wrong, I admit...) the water flow to the pump is restricted, causing the motor to cavitate and spin too easily. The computer never detects that current is high enough for correct pumping, so it continues to fill until the "overfill" pressure switch is triggered, which would explain consistent overfill without actually flooding.

 

Of course if I'm wrong and the pressure switch IS used for the primary water level detection, then a faulty or blocked pressure switch would give the same symptoms...

 

[richnz]

Is the drain hose high enough and is there enough pressure?

Is the water being siphoned out due to the drain hose because it's not high enough, so the machine has to keep topping up?

Does the GoPro show enough water being sprayed?

This G6860 had a pump issue where the top half of the impeller separated but it still half-worked.
The wash performance was poor though.
There were no error messages interestingly enough.

It tends to be turned on before we go to bed so it was a morning surprise that the wash performance was poor. I think it was poor for about 2 weeks but as it tends to be loaded to the hilt, I thought nothing of it.

One night I turned it on earlier and thought that it sounds wrong. It's quiet but the wash noise sounded sad. Then when I shut the door I heard a squeal from the pump and that was enough to prompt me to investigate further.

That's where I discovered the separated impeller. There was enough pressure to activate the pressure switch (So there was no error message from that) but not enough pressure to properly wash the dishes.

I do wish I had looked at the consumption figures.

 

[ozzie908]

The pressure switch on the pump

Is I believe connected to the heater not the actual water level in the machine its to ensure there is sufficient water to operate the heater.

My first place to look would be the water matrix usually on the left hand side as you face the machine check for any debris in it and maybe with a little luck you may see the problem as unless they have drastically changed the workings this matrix can and often does clog up with grot.

Good luck and keep us posted of your findings...

 

[henene4]

A clogged up water inlet would not cause a to high water usage.

It would explain the bad cleaning alone - not the high water levels, nor the high water usage, nor the long cycle times.

The pressure switch does at least play a part in the heating circuit, correct.

If it isn't used during load sensing, but later during heating, it would only make sense that the machine adds water until it does eventually trigger to be abled to heat again.
That makes all heating stages longer, may mean it never actually properly gets to temp (though that should give an error code if actually fails to heat) and gives the ever increasing fill levels.

It's a "to low" switch regardless of direct connection.

A partial pump blockage is unlikely here.

If the filters are clean - like the OP said - there are only relatively large connections between pump and sump (looks like half an inch or larger).

The big thing here is that anything that can truly fail otherwise would give different fault conditions in my opinion.

It's an electronically driven pump, so any non-total fault would still give you some error message.
Partial blockage is unlikely, all filters are removable and clean.

Water intake isn't the issue - the machine adds to much water, but dosen't go into a full overfill condition, so it can fill and stop filling.

The water amount counter obviously works right - I don't see how it could fail in a way where it would simultaneously display a way to high water usage and actually have the machine fill higher than usual.

So the machine is thinking it needs to fill for some reason.
And it fills till overflow - but when it reaches overflow, it correctly drains until that resets, only to try to fill again. That's at least how I understand the "drains only to fill immediately again".

The water levels get really high - but don't overflow.

And the only things realistically abled to tell the machine to fill are the water amount counter, the pressure switch or pump data.

That in total leaves said parts plus the control board and the connections to those parts to be problematic.

We ruled out the water counter and it's connections.
The control appears to be unlikely - that eratic behaviour while still being pretty much completely operational with no fault indication is rare.
It can't be an erratic pump connection since it doesn't get direct feedback even - that pump either is connected or not.

So it could be a pump issue - but we already said that's unlike for the same reasons.

It could be some wonky connection between the control and the pressure switch - since a disconnected wire just looks like an open switch.
Or the pressure switch itself.

 

[tomwasher81]

Thanks all for all the information and troubleshooting tips! I'm so grateful for the assistance!

Jerrod_six - to enter the service mode (with the machine turned off), hold the ok button, and press and hold the power button till it beeps. Then press ok three times and hold the ok button until the menu appears. if you press ok 5 times and hold it takes you to a second service menu.

Regarding a pump blockage - the GoPro footage shows the machine is spraying with what I assume is the correct pressure, and no problems appear in the footage.

The dishes come out clean apart from the occasional blocked bit of a dish or remnant on cutlery; it just takes 4 hours and uses 26l of water.

All the filters are clean, including the small plastic "smile" shaped filter that leads to the circulation pump. The non-return value is clear of anything as well.

I ordered a new pressure switch from Miele at the cost of £80 :-(, and I hope that solves the problem.

Sadly if it doesn't, and it's a £500 pump, I'm afraid it will be getting replaced with an Akso, Bosch or Siemens.

It's a shame it's showing this issue so soon; it's only 4 years old, but fingers crossed that the switch solves the problem, as it was not a cheap dishwasher.

My 3-year-old TOL Miele touchscreen washing machine was a nightmare and took 6 months of fighting, but I got a full refund and bought a Schulthess machine which is amazing!

I'll post an update once the part arrives in a week about how the repair goes. I thought you could do it without taking the pump out, but I think I can manage it.

Thanks, everyone!

 

[bewitched]

Hi. The machine doesn't use a pressure switch but a fluxmeter located in the water path on the side of the machine. The pressure switch fit on the pump is the heating pressure switch. It detects if there is enough water for the heater to turn on.

 

[henene4]

That part works correctly though - the usage report indicates a way higher water usage which are in line with the too high water levels actually observed by the user.

To be more exact on that:

These water flow meters are a rotating wheel, fitted with a magnet (or multiple) and a corresponding hall effect sensor next to that wheel.

Each time a magnet passes by that sensor, it's conductivity (I think it was conductivity) changes.
That registers as a pulse in the electronic control.
So, each impulse corresponds to a certain amount of rotation (a part of a whole rotation, or a whole rotation).
Each amount of rotation more or less exactly corresponds to a certain amount of water flowing through.

That allows the control to know how much water went into the machine down to the millilitres effectively by just counting up.

That could mean - if it wasn't reading correctly - it could read either to high or to low.

For it to read to high - to many pulses - these pulses would have to come from somewhere.
But, in that case, as unlikely as it would be, it would read a to high water usage, yes.
The water level in the machine would be way to low at first, though, normalising via load sensing.
It wouldn't be to high as described.

The other, way more likely route of failed would be to few pulses counted.
That would be a sticky wheel, basically.

In that case, though, water usage reports by the machine would be normal, but the levels are to high.

There is no failure mode of the water amount counter with the DW reporting a to high water usage itself AND actually having a higher water usage and the correlated issues (long cycle times, the overflow apparently triggering occasionally for short bursts of time).[this post was last edited: 2/18/2023-12:25]

 

[tomwasher81]

The machine is currently running on the automatic cycle. It's not as filled as usual, and I wouldn't say the dishes were that dirty.

So far, the machine decided they needed a pre-wash which used 3.8l of water, and now it's on the main wash and added 3l of water.

It added another 3.2l of water, taking the total usage at the main wash stage to 9.5l for pre-wash and main wash. I can hear there is too much water in the machine now. In the 5 minutes of writing this post, it topped up the main wash water 4 times, adding 3.5l of water.

Meanwhile, it's been on for 18 minutes, estimated 3:34 and is saying 3:22 after 18 mins, and the finish time is getting later, a minute at a time.

On another question about it - does anybody know what the Automatic adjust setting does? The manual states:

"You can adjust the Automatic programme so that it will remove stubborn soiling from a lightly soiled load. This will increase energy usage."

It is turned off but I wondered if turning it on would decrease the cycle time.