Miele 842 SCU Dishwasher intake/drain error F07

[hallm]

I have a Miele 842 SCU Plus dishwasher which I purchased in 2005 and I am wondering if anyone can offer me some guidance around a problem I am having. 

I am getting erratic wash cycles which results in the usual intake/drain error light. When I start the machine I get the usual draining of the sump and then the filling to do the first wash. Then the unit moves on to drain the water again and perform another fill. At this point, the unit will either continue washing until the full cycle is complete or, it will stop and throw the intake/drain light. It usually quits before the soap door gets a chance to open.

I accessed service mode 2 after the last intake/drain error event in hopes of getting a fault code that might help me.  In the 8 o’clock position, I get a solid green LED start light which my manual tells me is an ‘F07 error code, Too few pulses at flow meter/end of water intake’.

I disconnected the WPS supply line from the house supply.  The original washer had swollen and the plastic filter basket was about 70% blocked by the small bits of rubber from the washer. Thinking this was the reason for the F07 error I cleaned this out and installed a new washer.

When I ran the unit again on normal plus it completed the full cycle without throwing the intake/drain light and plus the error code had cleared.   It did this a couple more complete washes but now the F07 error is back.

The washer is back to the erratic wash cycles and it stops completely after about 5 minutes.

From my digging around on the web I think I might be dealing with a flaky switch or sensor that has a tendency to operate properly at times or not at all.  I am hoping you folks might be able to help me as to where to start first. Let me know if you need any further information.

Thanks in advance for any help provided.

Mike

[Naro Mohamad]

I think this is a problem with the flow meter or water pressure sensor in the dishwasher.
Need to check:

1. The flow meter is located on the water supply line, which is connected to the dishwasher.
2. Water pressure, low water pressure may cause the inlet/drain indicator to turn on. (the water supply tap must be fully open, and there must be no kinks or restrictions on the supply line)
3. Water inlet valve, the water inlet valve is responsible for controlling the flow of water into the dishwasher. If the valve is defective, it may cause the dishwasher to stop in the middle of a cycle or display an inlet/drain error. (You need to check the valve with a multimeter to make sure it works correctly)
4. Check the drain pump, a clogged or faulty drain pump can also cause the inlet/drain light to come on.

I also found a video on YouTube. Intake Manifold Light Flashing - FIXED WITH PLUG IN 5 MINUTES.

Watch the video if it helps solve the problem. Of course, I'm not an expert in this, but just a developer of computer monitoring software.

[hallm]

Naro thanks for taking the time to reply to my question and I appreciate the suggestions you have made. 

Scott the Fix It Guy has a lot of helpful videos and I have been in touch with him as well.  When I explained the problem to him he felt the issue was related to the two inlet solenoids inside the WPS unit.  He has suggested that I replace the unit with a new WPS or purchase an aftermarket solenoid as a replacement.

His comments made me check the WPS connection to see if there were any blockages present, and that was when I found the degraded washer issue. When I cleaned out the rotten washer and the small filter basket inside the WPS unit I thought this restriction was the problem I was facing.  In fact, after I cleaned it out the dishwasher ran properly for a complete cycle and it even cleared the F07 fault code. J  Great I thought, the water flow problem was fixed!  Unfortunately, the F07 error occurred again after a couple of cycles. L   So there must be more to this than just the WPS unit if it ran fine for several cycles.

Our water pressure in the house is pretty reliable and doesn’t vary much so I think I am good that way.  I also replaced the drain pump motor 2 years ago when it developed a seal leak into the bottom pan and tripped the float.  Whenever I start a new wash cycle, I get a strong flow from the drain pump into the house drain, so I think my drain pump it still good. I also put in a new pump partition, impeller, and motor capacitor while I was replacing the drain pump.

I do like your suggestion about the water inlet valve possibly being an issue. Digging through the technical manual for the washer I am considering the magnetic reed switch that is part of the flow meter. It takes 200 pulses per/ltr to let the washer know water is moving in the system properly. I am thinking I might have a flakey reed switch that might be acting up at various stages in the cycle to cause the error.

I am hoping others might chime in with any other things I should consider.

Thanks again

  Mike

[hallm]

I have posted this content in hopes that it might help another user who is having similar issues with their Miele dishwasher.

I have solved the problem I was having with my Miele 842 SCU Plus dishwasher. First a big thanks to Scott The Fix-it Guy.  Scott has a large knowledge base of YouTube appliance repair videos including those related to Miele dishwasher.  After sending Scott a detailed list of my machines symptoms and error codes, Scott was able to narrow it down to a couple of possible items to check.

He said the symptoms and error codes I was getting had him suspecting the heater/pressure switch (level indicator on my parts listing) and/or its electrical connector.

He also said that the water intake solenoids in the WPS (water protection system) could be getting weak and not allowing the machine to fill properly at the various cycles. The WPS is very expensive part to replace if ordered from Miele Canada, almost $400 Canadian dollars, he suggested using a generic fill valve available from Amazon as a cost effective fix. He pointed me to one of his YouTube videos and how to install a new generic valve.

When I checked the WPS I discovered that the 20 year old rubber washer used to seal the connection to the house water line had slowly disintegrated and small bits of the rubber washer had slowly clogged the fine filter basket blocking the inflow of water to the water valves.  Once I cleaned this out the washer bits and installed a new rubber washer the machine ran fine again for a few more weeks.

Slowly the symptoms returned to the point where the washer refused to move beyond the first drain and fill cycle without throwing the infamous intake/drain error light.  Since I knew the water intake was not an issue now so I moved to possibly replacing the heater/pressure level switch at a cost of $115 from Miele Canada.

The new switch was installed and the almost 20 yr old washer is back online and washing dishes again much to the relief of my wife and I as we hate washing dishes!  If you run into problems with your machine check out Scott The Fix-it guy.  His knowledge base and his willingness to help people is amazing.

Mike

[hallm]

Scott TheFixItGuy has posted a YouTube video which shows the replacement of the heater pressure switch (level switch) which corrected the problem I was having with my machine. Hopefully this helps another Miele owner.

 

[JeffreyK]

I have a solution that worked for me on my 842SC Plus.

I would press the start button and like normal, the sump would drain (30 seconds or so). After that, the water would start to fill and within a minute or so it would stop and the intake/drain light would flash. Sometimes it would drain, and sometimes it would stop full of water. It didn’t happen all the time but when it did, the machine would be completely out of commission. I’d try it again in a couple days and it would work for a few washes before the problem returned.

I replaced the high level switch. Spun the impeller motor with a fork-which was free moving anyways. Cleaned the impeller pump and the supply/drain lines. Checked the motor, heater element, circuit board and (almost) every other component with a DMM. I even went so far as to disassemble the circuit board and reflow all the solder joints, as well as cut apart the WPS and check the magnetic actuator for the intake. Nothing worked long term.

I disassembled the right side of the dishwasher to get access to the intake system and found the problem: there is a spinning wheel encased in the plastic that operates the reed switch to tell the control unit the volume of water being passed through (200 pulses per litre). There is a teflon(?) coating on the blades that had expanded and bubbled over the years, which prevented the wheel from spinning in the case. The machine would then interpret it as the intake wasn’t flowing so it would shut down, drain (occasionally) and flash the intake/drain light.

I carefully cut the plastic around the wheel and cleaned the bubbled coating off the blades, then reinstalled it and welded the cover (using a torch, butter knife and spare PE plastic for filler). I ran water through it to check for leaks, welded some more, then put it all back together and tried it.

Success! The dishwasher now works better than it ever did (it came with the house and was already 7 or 8 years old; this happened after another 10 years of ownership) and the intake/drain light hasn’t lit up since. that was in August of 2022 and it is used daily-sometimes multiple times a day.

I’m not saying that everybody should attempt this repair, or that it will work for your model. Miele has the entire intake assembly available for about $225 CAD (P/N 5457191), but I wanted to see if this would work first. It absolutely did and cost me nothing but a couple hours of my time.

So if you’re pulling your hair trying to figure out what the heck is wrong with this dang machine and have replaced a metric s***-ton of parts with no real results, check the reed switch wheel inside the intake assembly under the right side access panel (right side as you stand in front and look to the door on my model).

Long winded, but hopefully this helps somebody.

 

Thanks for reading,

Jeff K

Sherwood Park, Alberta