Miele W844 Pump run on problem

[Dbuck]

Miele W844 washing machine.

The cycle finish fine but the pump runs on and does not stop. You can open the door and then it stops

The drum is empty and water is pumped out fine.

Checked the filter and all is clear and the pump impellor is fine

This machine uses a pressure transducer to measure the water level - tried disconnecting the tube to this and the pump still runs on. 

Are there any other sensors that will keep the pump running at the end of the cycle?

Thanks

 

[Whitegoodshelp (Andy)]

Hi. If the pressure system was at fault it would cause other symptoms on wash, rinse or spin. If the washing machine otherwise works ok I wouldn't suspect the pressure system. There could be an overfill protection on the pressure system, that would fire up the pump if it thinks it is overfilling, but that would also cause it to fault on the wash cycle. Potentially if it thinks it is leaking it may energise a pump to get rid of the water. Check the base of the washing machine for a float switch and system.

[Dbuck]

Hi Andy,

There are no visible leaks and the inlet solenoid is tight. I've looked around the bottom of the drum and there don't appear to be any sensors there - no float or pressure switches or wired sensors. I've checked the tubes around the pump for blockages and all is clear. All I can think is the pressure sensor is also used to detect the water has been cleared by the pump at the end of the cycle - maybe the zero has drifted but I don't know how to check this or reset the zero. Also as standard the washer will let a small amount of water back into the drum at the end of the cycle (I assume to prevent any smells) but I'm not sure how this is measured and controlled. Its really strange. I need a time server Miele guy to reply maybe.

[Whitegoodshelp (Andy)]

Hello. If it was the pressure system the washing machine would not function without fault or error. Does it complete a wash cycle ok apart from right at the end? I can’t think how the pressure system could have a fault that only shows after the last spin. My article here might be helpful and explains about the pressure system and common faults - how a washing machine controls water levels

[Dbuck]

Thanks for the information but this Miele washer appears to use a different sensor (pressure sensor with analogue output)

See images of the sensor and fitted to main control board - but as you say this but must be working or the machine would not fill and run through the cycle.

 

 

[Whitegoodshelp (Andy)]

Hi. That’s a novel one. I would expect it works in the same way though. Water creates air pressure that activates a switch. I can’t imagine any other way it could work. 

[Whitegoodshelp (Andy)]

I presume the rubber tubing goes to a pressure chamber bottle on the outer drum?

[Dbuck]

Hi Andy,

Yes the tube goes into a plastic syphon vessel at the bottom of the drum, I assume that as water rises it creates pressure in a large vessel which is amplified as it goes into the smaller tube pressing on the sensor - there must be an analogue output into the main PCB which will be related to level as opposed to a single trip level. This may be used to adjust water volumes for different cycles and efficiencies (It has a water plus button for adding more water). Allegedly you can connect a PC to the main board but I don't know how to do this ? this may have options to change programmes and reset this water level transducer.

However I still cannot understand why the pump continues to run on at the end - it even allows you to open the door in this state and the pump then stops and will not restart until the next wash is done.

Nice system and has worked fine for years but awkward to fix without the knowledge.

 

[Whitegoodshelp (Andy)]

Yes only Miele engineers with a specific computer program can connect the washing machines to a laptop. Miele's pressure system looks quite different but essentially it will work in exactly the same principle. Air pressure created by water level which either activates a switch or is measured by a magnet moving inside a coil or some other form of electronically detecting pressure. As we have discussed and both agreed if there was a fault on the pressure system the washing machine would not function properly. If it functions perfectly okay apart from this not shooting the pump off at the end then it is illogical that it could be caused by a fault on the pressure system. It's probably more likely to be a fault on the PCB but of course they are going to be extremely expensive on a Miele washing machine. And it would be very risky indeed to try and fit one with no guarantee it would fix the fault. 

[John O]

I have the same problem.  Upon completion, my Miele washing machine continues pumping even if the water is completely drained (or as much as is possible).   My Meiele edition 111 W3371 will run a full cycle, rinse, spin, drain and the pump will continue running.   It was clean when I bought it (used), but I have cleaned it, cleaned the traps, and looked for any obstructions.    Opening the door stops this behavior but I'm thinking if we step out and the pump continues running it will cause undue wear and tear on the pump.    As partu of my job I had learned all the do it yourself fixes for the Whirlpool duet series, and  have done a number of repairs on my own for a fraction of the cost of having a tech come to the house.  Whirlpool now only contracts with Sears and offers zero assistance for repair on their appliances now, so I was left to my own devices with 100% success in fixing my home washer and drier.

Have read a few of these posts already, there seems to be a lot of general "how to" and "it should work" kind of answers that look rather cut-and-pasted to me.    I can't decide here that the pressure switch is or is not a part of this problem.  The last thing I would ever do is pay for a guy to come to my house with a laptop to fix my washing machine.   Living in Norway I suspect such a visit would likely cost more than I paid for my washing machine so it's certainly not an option.

A brief glance online the pressure sensor is £5.45 (analog) and I'm inclined to replace it rather than spent tons of money and time figuring out what is the problem to, just to buy a £6 part.

My experiences with almost anything mechanical is that certain symptoms lead to specific problems, or a specific range of problems.  Nothing is more frustrating than having a support person tell me (or anyone else) "that shouldn't happen".

What part of the system tells the pump to run?  I'm gathering the pressure valve or sensors (electronics, likely) have something to do with water level detection.   I prefer float valves and bubbles, they are more reliable but here we are.

 

[Whitegoodshelp (Andy)]

Is there a float switch in the bottom of the base that detects leaks that could be stuck, all actually been energised by a leak? If a Miele washing machine thinks it is leaking it may energise the pump to get rid of the water though to be honest it should abort the wash cycle too.

Other than that, as mentioned before if a washing machine thinks it is overfilling because the pressure switch is stuck on an overfull position it will energise the pump. If it thinks it is overheating it may also energise the pump to get rid of the excessive hot water although again, all of these faults would cause the washing machine to malfunction and abort on a wash cycle.

So if the washing machine otherwise works perfectly okay then all of the normal causes should be discounted. I would definitely check for the float switch in the base though because I recently had a dishwasher that was also leaving the pump running after a wash cycle and it proved to be stuck float switch in the bottom.

Other than all of that it has to be getting power erroneously from the PCB, unless by any chance it is wired up where everything is live and all of the on and off switching is done on the neutral side, which I don't know if anybody even does that any more, but an earth leak on the pump could theoretically cause that.

[MikeH]

Hi all,

I have EXACTLY the same problem occurring on my Miele washing machine. I'm wondering if anyone got to the bottom of what appears an identical problems to give me a few suggestions?

The washing cycle finishes correctly, but the pump runs on and does not stop. If you open the door and then it stops, close the door and the pump restarts. If you turn off the washing machine power (front switch) then the pump stops but the pump does not continue running when the power is reapplied. This problem does not happen all of the time - maybe 50% of the time. Also, it seems to happen more with a heavy load, but this last claim is not 100% established.

The drum is empty and the water is pumped out, although sometimes the clothes seem wetter than normal when the problem occurs. Another spin cycle dries them completely.

I have checked the filter and it is clear and the pump impeller rotates.

initial suspect areas that I can see are:

1. Pipes and positioning - possible blockage unlikely as there have been no floods, however a pipe may have shifted or got jammed behind the machine.

2. Water level sensor - quite possible.

3. Inlet valve - Not really a good suspect as the washing cycle seems to execute properly in this regard.

4. Drain pump - Not really a good suspect as all water visible through the glass door seems to have pumped away.

5. Electronics - Possible but unlikely since I only have this one mode of failure at the end of the cycle, nothing at any other point. The problem also seems suspiciously like the same problem that others have had, making a random electrical failure unlikely.

So I tend to think about checking all pipes and the water level sensor as a first step. Am I missing anything? Any suggestions as to where to start looking if the above thinking is flawed? I can generally fix most household problems & I'm an electronic engineer.

Cheers!

 

Edited May 2, 2022 by MikeH
more detail added.

[Whitegoodshelp (Andy)]

Hi Mike. If the pump is still running, it must be getting power. But the things that are likely to cause the pump to keep running are all faults that should affect the washing machine performance and cycle.

So for example, if the pressure system is blocked, and the washing machine is not receiving the signal that the water has pumped away successfully, then it will cause a fault on the rinse cycle. And it will also prevent the washing machine from spinning.

The other theory regarding a float switch detecting a leak and energising the pump is also something that would cause the washing machine to fail during the wash cycle, and indeed to abort cycle.

So if the washing machine functions perfectly okay, carries out the wash cycle rinse cycle in the final spin, then I can't see how it could be any normal fault, and can only assume there must be a fault on the main PCB.

When the washing machine has finished all of its functions and the cycle is complete then the PCB that controls everything should simply switch off the pump and end the cycle. After the washing machine has completed the spin, it's not actually waiting for anything. Everything has completed successfully. Is not waiting for any signal that the water has gone, it had that prior to deciding it was okay to go into full spin. All it is doing is keeping the pump running for a set amount of time after the spin is completed and this time is only governed by the software running inside the PCB.

 

[MikeH]

Hi Andy, Many thanks for getting back so quickly. If it is as you say (and I have no reason to doubt it) and the computer is not waiting for any signal at the point when the spin completes then the fault must be with the PCB - nothing else makes sense. I just feel a bit uncomfortable about this because:

1. The final delay for which the pump runs after spin completes will just be implemented as a software timer in the microcontroller and it's hard to see how this would fail but every other bit of the programme run flawlessly. For example, all of the timers that control the wash length, spin length etc. It is possible though that this timer function uses some instructions not used elsewhere, or the memory is corrupted somehow.

2. Other people seem to have had exactly the same problem.

3. For me, at least, the problem doesn't happen all of the time, and when it does happen, the washing is often more damp than I would expect.

However, I take your point that no other explanation makes sense at all. 

Again, many thanks for your help and quick response.

Mike.

 

[Whitegoodshelp (Andy)]

Hello Mike. Yes, I agree with your points. It's a very strange fault indeed. If you say when it happens the washing is usually not spun properly, could it be a fault that's just not triggering an error code? Maybe it is struggling to balance certain loads and doesn't have a proper system for pointing this out.

Some washing machines don't work very well if it can't balance the load properly. They can refuse to spin or only spin at a reduced speed. Sometimes they can even stick on the spin cycle for 15 minutes or more, constantly revolving the drum and trying to settle the load down. However, a Miele washing machine should be more than sophisticated enough to deal with this.

My mother-in-law has an AEG washing machine and she put a door mat in it the other day. She rang me up saying it was just stuck on the program going round and round. It had been stuck for so long she believed it had gone faulty, but I told her it might be struggling to balance a single bulky item. When she tried a normal load it was fine.

So clearly the AEG is dumb enough to be totally thrown by a single bulky item, and did not indicate with an error code that it just couldn't balance the load. But like I said, I would expect a Miele to be clever enough to give up after several minutes and just switch off with an error code saying it couldn't balance the load so didn't spin fully. But that's the only "fault" I can think of that could happen at that late stage.

The only other wild thing could be that earth faults (that is low insulation on specific parts) have been known to cause some weird faults on washing machines. But again, if apart has a low insulation it has low insulation, so it's hard to imagine it being so intermittent and only manifesting right at the end of the cycle.

[MikeH]

Hi Andy,

Many thanks again of getting back so quickly. Do you know if there is a diagnostic mode that I can access in the Miele W1714 that may give any clues? I saw something on YouTube about powering on the machine with the start button pressed, then pressing the start button three times... However the video was in Russian and I couldn't work out much more than that.

Fortunately the washing machine does function, so I hopefully have a little time to try and figure this out. If it is the circuit board, I haven't managed to find an available replacement at the moment.

[Whitegoodshelp (Andy)]

Hi Mike. No, I don't, information on Miele technical things like that are fiercely protected by Miele. I definitely wouldn't try replacing the pcb, they are way too expensive to replace with just a fair hope it will fix a fault.

[MikeH]

Hi, I just thought that I would report back to potentially help anyone else with the same problem in the future. After every wash day, we have always turned off the washing machine using the front panel switch. So when I had this problem with pump run-on, I thought that this off/on operation would cause the microcontroller to reset, eliminating a recoverable problem with the uC in a strange state. Anyway, I tried turning off the washing machine at the wall (complete 2-pole power removal for about 30 minutes to ensure any internal capacitors would discharge) and the problem has not occurred for at least 3 weeks, and the washing machine is used several times most days, so that is a fairly long test. I had always assumed that the front panel switch is a hard 2-pole power removal, but I never checked this out. I still don't know whether this is the case, but the above does seem to have fixed the problem..... The only other thing that has changed in the last few weeks is the temperature with the warmer weather arriving. However, I don't think this a likely inadvertent solution since the washing room is in a centrally heated utility room and never gets particularly cold, even in winter, but it is still a possibility.

Anyway, I'm posting this in case it helps anyone out in the future.....

[Whitegoodshelp (Andy)]

Thanks for the update Mike. Yes these days you have to turn many things off completely at the wall socket for at least a few minutes to truly turn them off.

[MartinC]

In case it helps anyone else in future, our Novotronic W1512 had the same problem i.e. the pump was running on after completion of the drain and spin at the end of the wash.  In other respects the machine was working correctly i.e. it was not over-filling, it was draining correctly and was completing all programmes without problem apart from the pump continuing to run at the end of the programme. 

I checked all the usual suspects i.e. the outlet hose, the pump filter and the pump inlet pipe, and all seemed fine.  It was also possible to blow through the air pipe that senses the water level from the control board end.

Having tried everything else and failing to solve the problem, and despite the water level pipe seeming not to be a problem, I removed the plastic housing at the bottom of the drum to which the water level sensor air pipe fits  (front central location on the outer drum - it just pulls out from the rubber seal in the outer drum after pulling out one plastic fixing pin on its upper righthand side).  This was almost competely blocked with a thick gunge.  To be honest, I don't know how the the sensor was managing to detect the water level at all, which it clearly was because it was filling to the correct water level to wash and rinse.  I also did a 95 degree wash after cleaning and refitting it  to make sure everything in the bottom of teh machine was clean. 

The problem has not returned after 5 washes whereas it was previously happening every wash so I think the problem is now solved.

[Whitegoodshelp (Andy)]

Many thanks for the update, Martin. It looks like the consistency of the gunge was such that it didn't cause a proper blockage, and the washing machine otherwise appeared to work OK. Presumably it would have eventually blocked solid and malfunctioned.

The nature of pressure chamber blockages is sometimes one where a blockage may not be solid, and may allow some air to get past it. In such case, there is only a problem when the water drains out. This is because the sheer volume and weight of water inside the drum can easily force past the gunge, and so the pressure switch operates OK. It may be that a bit more water is needed, but it will usually go unnoticed unless it's excessive.

However, when the water is being pumped away, it only drains from the pressure chamber through gravity. So the very small amount of water that has entered the pressure chamber gets trapped. This is what can hold the pressure switch in the on position.

The only thing that is strange, is the washing machine's reaction to this. It should be triggering an error code saying that the water is stuck inside the washing machine and it hasn't rained away properly. This is because without the pressure switch turning off the washing machine will still think there is water inside. I can only assume that because this is right at the end of the cycle that it is some sort of oversight or anomaly. The washing machine is still trying to drain the water, hence the pump continuously running, but it should not just keep running indefinitely, so this is arguably some sort of bug.

There is every chance that with the washing machine displaying this sort of behaviour if it is ignored in the washing machine is just switched off, that by the time being used again a few days later the pump may well have stopped running because the water trapped inside the pressure chamber has very slowly drained away, releasing the pressure switch. However, I mentioned this just out of interest, and not as a recommendation. Any blockage inside a pressure system is bad and needs fixing ASAP.

 

Update: I just want to add that there must be an explanation as to why the washing machine goes into spin, which it should never do if the pressure switch is jammed on, and yet continues to pump phantom water out when it is finished. One possible explanation is that the pressure system used is not necessarily a direct on off system and may somehow register the actual pressure. So it could be that the pressure switch does register that the majority of the water has been successfully pumped away but does not switch off completely to a satisfactory level.

 

[NickNak]

For what is it is worth, I had the same problem as others on my Miele W1:  drain pump would run-on after the cycle had finished, even with the door open, after cycling power, left for 3 days, etc.   The machine registered a "drain fault" when it tried to run a cycle as it pumped out the water as fast as it could fill.

I resolved it by opening the back and attaching and reattaching every plug on the Printed Circuit Board.   Somehow it reset the voltages or maybe a loose connection or discharged a capacitor or who knows?   Anyway it worked perfectly.

Furthermore I know the solution works, because 3 years and many thousands of washes later my machine did the exact same thing - pumps running on.  I did the same and it is resolved again.

A lot cheaper than a new PCB, which would be the Miele solution.

The design is pretty strange as the two pumps actually are powered directly from the PCB itself.   There are no external relays.   It is a pretty low power (50W or so for each) but for a PCB 100W is quite a load.   Searching for a relay is what drew me to the solution.

Anyway I hope that that might help someone else somewhere sometime.   Good luck!

 

[Whitegoodshelp (Andy)]

That's very weird, NickNack. Very illogical but good that it stopped.

I can't remember if I mentioned this earlier but some washing machines have a leak detection system built into the base of the washing machine. If this switch stuck, or if there was an actual leak, the pump can remain energised even when the washer has finished. This would be to try and get rid of the water inside the washing machine, which the controls believe is a priority.

 

[NickNak]

Thanks Andy

That makes total sense.   I did originally look at the "flood" switch 3 years ago and could not find anything wrong.   Last week I just reverted to what worked last time, which worked again this time.  It is hard to imagine disconnecting and reconnecting the plugs at the PCB would do anything to the flood switch, but who knows?

Anyway I hope it might help someone else.    It is 5 mins work to try it.

On a totally different topic - I modified my European (50 Hz 220V) Miele machine to run in the US at (60 Hz 220V).   If ever this comes up I found a solution, after having thought (and told by Miele) that it was not possible.