Miele Dishwasher faulty

[akis]

Hello

I have been trying to repair an old (11 years) dishwasher, it is a Miele G1040.

The symptoms are that it starts, drains the old water, intakes clean water, and starts the jets. The jets operate for about 10 seconds. Then they stop. This start/stop of the jets continues approximately 10 times. Then it flashes all 3 orange lights, drains out the water, and stops.

I have done some more fault diagnosis and repair but the problem still exists

1) Firstly I removed and repaired the water pressure valve which had water inside, cleaned it and resealed it, made sure it works (by blowing on it while testing with the multimeter) and you can actually hear it click when the circulation pump goes.

2) Secondly I removed and repaired the heater relay, it was all blackened and carbonised inside, I brushed the contacts clean, it's like new. Its coil is fine and you can also hear it/feel it activating.

3) I removed and tested the water temperature NTC, it works as described, around 13K Ohm at 23C and goes down with temperature increase.

4) I measured the water heater element, it is 24R, at 240V it would draw 10A, therefore 2.4KW, exactly as stated on the plate

5) During the "fault", when the water jets operate, 6 seconds in, the computer tries to activate the heater, you can hear/feel the relay going, and you can see an intake of current (up to 10A), but it is momentary, it cuts out almost immediately, the water jets operate for another 3 seconds and then the "stop/start" cycle ends. It does this around 10 times before giving up.

It seems to me the machine is fine, it goes through its normal steps, and when it comes to heating the water, it tries, there is a flash of incoming current, but for some reason it stops almost immediately.

There may be another sensor which the machine consults and it forces it to cut out. I have not seen any on the diagram however. 



Any help appreciated.

[Circlotron]

A non-computerised dishwasher we had some years ago developed a similar fault. There was a partial blockage somewhere around the pump assembly so that when the spray started it would wrongly send pressure into a hose connected to the pressure sensor that detects too high water level. Pump would stop and reverse to begin emergency procedure of emptying out what it thought was excess water. That would relieve pressure from the high water sensor and so it would go back to wash for a few moments etc etc.

[CJay]

A non-computerised dishwasher we had some years ago developed a similar fault. There was a partial blockage somewhere around the pump assembly so that when the spray started it would wrongly send pressure into a hose connected to the pressure sensor that detects too high water level. Pump would stop and reverse to begin emergency procedure of emptying out what it thought was excess water. That would relieve pressure from the high water sensor and so it would go back to wash for a few moments etc etc.

Mhmm, that happens with washing machines too, they clog the level sense pipe with crud and undissolved detergent.

Cleaning all the pipes, including the drain pipe and making sure all drain holes/ports are clear would be a good step to take.

It's a foul job.

[Towger]

Assumptions

Miele = Loaded with sensors and designed to last 20 years...

Is there error(s) codes or LEDs flashing??

Possible: 1. It thinks there is a fault with the heater.
              2. It thinks there is a fault with the Jets or Water Supply etc.


Manual: https://www.manualslib.com/manual/528037/Miele-G-1010-I.html#product-G 1040

[bd139]

Moment error codes appear on white goods, I hit ao.com instantly. I'm not getting dish washer skank all over me again. It's really not pretty.

[akis]

The fact that it switches the heater on for fractions of a second means it's running a program that says "heater on" and then probably "if X sensor says Y then stop heater". Something like that.

I have disconnected the heater and the cycle stays exactly the same. It still switches the heater relay on and then immediately off again. The difference now is that there is no influx of current, even momentarily.

" I'm not getting dish washer skank all over me again. It's really not pretty."
Nah, it's really very clean, surprisingly so. Lots of water on the floor every time I drop it on its side though. But clean water.

[tautech]

Assumptions

Miele = Loaded with sensors and designed to last 20 years...

Is there error(s) codes or LEDs flashing??

Possible: 1. It thinks there is a fault with the heater.
              2. It thinks there is a fault with the Jets or Water Supply etc.


Manual: https://www.manualslib.com/manual/528037/Miele-G-1010-I.html#product-G 1040

    3. Wash starts, senses low water, stops heating, stops wash---water level recovers, repeat.
Quick check, add more water.
Suspect blocked water inlet filter.

[alanb]

Can you get it into self diagnostics mode? The process and the error codes are shown the technical manual in Towger's p;ost.

[akis]

Can you get it into self diagnostics mode? The process and the error codes are shown the technical manual in Towger's p;ost.

I cannot see where this is in the manual. I can see how to "reset it to factory settings", which I have done a few times.

[quote
    3. Wash starts, senses low water, stops heating, stops wash---water level recovers, repeat.
Quick check, add more water.
Suspect blocked water inlet filter.
[/quote]

There is enough water, and adding more does not change anything. Incrementally checking until it starts leaking out of the bottom of door. Even filling it in with kettle-hot water to dislodge any stuck gunk.

[alanb]

This is a link to the technical manual

https://www.manualslib.com/manual/801663/Miele-G1000.html?page=112

I think the other link was for the user manual

[Towger]

I have disconnected the heater and the cycle stays exactly the same. It still switches the heater relay on and then immediately off again. The difference now is that there is no influx of current, even momentarily.

One thought was it is detecting earth leakage from the heater element, but this seems to be ruled out.  This is a serious fault, so it should shutdown, not try again 10 times.

The 10 retries is interesting.  Is there any sort of current monitoring on the heater circuit?
Have you taken the controller board out and visually checked it for burnt/dry/cracked joins etc?

[HighVoltage]

I had to repair our Miele dishwasher with a similar problem and it had a water level sensor underneath the dishwasher in a large water capture panel. All I needed to do was to clean this panel and the water level sensor and all was good again.

Miele is not as good as it used to be but still probably one of the better brands.
We can order replacement parts in Germany from Miele but they have gotten outrageously expensive, compared to 10 years ago.

[Towger]

From Page 47:

Heater Pressure Switch, B1/13
The heater pressure switch B1/13 is located directly on the circulation pump and
registers the water pressure when the pump is in operation.
Using the pressure switch contacts, the heating is controlled via 2 poles. The heating
is switched via a heating relay located before the pressure switch contacts in the
circuit. Heating activation occurs during the wash and final rinse cycles.
If the circulation pump and heating relay are activated and the heater pressure
switch reset contact is open, the control registers a water intake fault, see Fault code
F14, 6.8.15.

I read this as:
  Turn on the Heater.
  Check the circulation pump is running, by checking the pressure switch.
  If the switch is open shutdown.

[akis]

Using the technical manual I have now been able to read the fault code which is F14 and it indicates a problem with the heater pressure switch. It explains (in another section) that if the system detects voltage coming from the pressure switch after the circulation pump has started and there is adequate water, then it assumes there is no water or that the circulation pump is faulty/weak/intake blocked, or finally the pressure switch itself is defective.

So I took out the dreaded pressure switch and yes it is soaking wet, obviously when I "repaired it" I did a botch job and it is leaking water inside the contacts. As a result it confuses the computer which thinks it has not switched over at all.

I am now going to buy a new switch and try it on. It is not guaranteed that this will fix it, because this switch was not leaking yesterday, so I think there may be more than one concurrent faults at play.

"
1) Firstly I removed and repaired the water pressure valve which had water inside, cleaned it and resealed it, made sure it works (by blowing on it while testing with the multimeter) and you can actually hear it click when the circulation pump goes."

Obviously it "clicks" and it reads perfect when "dry", but fitted on the machine and waterlogged it still clicks but leaks currents... What a bad repair I made!

[JXL]

My Miele dishwater had the same symptom.  The cause was a sticky circulation pump (not the drain pump).  Miele sells a special tool (looks like a stubby tuning fork) to free the pump.  That worked for a few weeks, and then the pump got stuck again.  After a few months, the tool was not able to free the pump anymore, so I replaced the pump.  A few more months went by, then the same symptoms again.  This time the pump was not stuck, but it was the pump motor which released its magic smoke.
Instead of paying for a new motor, I decided to replace the whole dishwasher (with another Miele).  First one lasted 12 years without problems, so I hope this one will go at least that long.

[akis]

To everyone who replied and helped, thanks, and thanks for the service manual link, with which I was able to verify the fault codes, in the end it was the pressure valve/switch which I thought I had repaired but it was still leaking water inside and causing shorts. I replaced the pressure switch with a cheap one from ebay and repaired the heater relay (again) which also had water inside due to its position and water spilling on it. The dishwasher has been working fine ever since and actually the glasses are now sparkling clean and it finishes quicker, I think the problematic heater relay and pressure switch were causing all sorts of issues that went undetected.