Bosch Dishwasher runs with door open or not al all and behaves oddly
I have a Bosch SHX57C05UC dishwasher. While it was running today, it made a kind of hammering noise and then started overflowing. I was out, but my wife turned off the water and left it until I got home.
When I got home, I turned it on, and it automatically started draining. I assume the emergency drain was triggered. The odd thing is that it didn’t matter whether the door was open or not. On a hunch that it related to the door switch, I took the door apart and checked the switch. The switch reads fine.
I took the kick plate off, and there was indeed water in the tray, so that probably explains the draining. I used towels to clear the water out.
I turned the breaker back on so I could run the diagnostic tests (which I had just found), and I can’t tell if it’s giving me something useful or not. The diagnostics show lights B and C blinking, which points to the inlet water value. The reason I’m not convinced is that pressing any other buttons causes all kinds of odd effects. I’m not sure that I’m not ascribing meaning to a random combination of lights.
With the power back on, I tried turning the dishwasher on. It launched immediately into a wash cycle, even though the door was open. I played around with choosing cycles and opening and closing the door (which had no effect). During one cycle the washer started howling at me and continued for about a minute after I turned the washer back off. It seemed to be coming from the left side of the washer, where the water line comes in. I put my hand on the water line, and I could feel the vibration. After a few more cycles of turning it on and off, it switched from running regardless of whether the door was open to refusing to run, and that’s where I am now.
I’m looking for some confirmation that a bad intake valve would cause what I’m seeing before I pull the washer out of the wall to go any further.
Aha! I just figured out how to used the diagnostic test correctly. I get E6, which is the water sensor. To use the diagnostics correctly, hold Power Scrub and Regular buttons and power it on. The display will show C1 and then P0. Press Regular again, and the display should change to P1. Press Quick to start the diagnostic test. DO NOT press Quick when the display shows P0 or P3. That’s bad. P1 is the only option that’s useful. Here’s my reference doc.
I should also add that when I try to run a dishwasher now, it acts like the door is open. The little red “active” light does not come on. I have a dishwasher full of water, and I’d like to drain it, but the drain function doesn’t no anything. Again, acting like the door is always open. Maybe I didn’t get the door switch put back in correctly?
I just took the door apart again to make sure I didn’t do something wrong with the switch. Nope. Switch is perfect. It’s doing everything a switch should do. The signal that the door is closed is definitely making it to the control board.
One more detail. When I was testing that the door switch is working, I noticed something that might be odd. Testing voltage from N on the power switch to the closed post of the door switch, I get 120V, which is expected. Measuring to the open post of the door switch, I got 110V, which seems odd to me, but I guess could be normal? (Tripping the switch causes the posts to swap, as expected.)
New behavior to report! I noticed that if I close the door hard, the washer begins draining, but it only lasts for about 1 second, then it shuts off again. Closing the door gently (less than hard) has no effect. I struggle to see how that can be anything other than a bad door switch. BUT, when I took the switch out, I could see with a meter that resistance across the closed posts was 0, across the open posts was infinite, and they swapped when I triggered the switch. Could it be that the switch is failing in some way that affects the current/voltage, but not the resistance?
I finally managed to get the washer to drain by manually triggering the emergency flood switch, which apparently works whether the door is closed or not.
Current state: I strongly suspect the door switch is bad. I also strongly suspect that one of the valves or sensors is bad. (Dishwashers don’t normally howl.) I am inclined to think that the control board is OK, but I would really love some external validation. If the control board is fried, cheaper to go buy a new washer than replace the control board, the bad value/sensor, and the switch.
I pulled out the washer this afternoon, took it completely apart, cleaned everything out, and put it back together. I found a build-up of gunk on the filter inside the water inlet valve. It looked like enough to be blocking water flow. I also checked out the turbidity sensor, and it passed visual inspection.
After I put everything back together, I powered it up (outside with no water attached), and noted no difference in behavior. The washer doesn't seem to recognize that the door is closed. While I had it lying on its back I noticed again that if I closed the door hard enough, the drain pump would run for about a second and shut off again. After I stood it upright again, it went back to completely ignoring the door, regardless of how hard I closed it.
I finally got some time to dig a little deeper. First I built shunt to replace the switch, so that the washer always thinks the door is closed. With the shunt in place, it still acts like the door is open. The switch is officially exonerated.
I also tried connecting it back up to the water supply to see what happens. Being connected to the water (with the shunt in place) did not change whether the washer is willing to run. It still won’t run. What does happen, though, is that the washer fills with water without me doing anything. I didn’t give it the chance, but I’m will to bet it merrily would have overflowed.
As before, I was able to manually trigger the float switch to get the washer to drain the water. That is the only way to make the washer drain. Activating the drain function from the controls has no impact.
To debug the intake valve, I turned on the water and unplugged the dishwasher. It still filled with water. Bad sign. I then plugged in the dishwasher and manually triggered the float switch. With the sensor triggered, the washer still filled. According to what I read, the float switch is in series with the intake valve, so triggering the switch should shut the valve. It didn’t. Bad sign. I took out the intake valve and pulled the solenoid off the valve. No matter what I do with the solenoid, I can’t get it to retract the plunger. My guess is that there’s a short somewhere inside it. Looks like a new intake valve is $15 on Amazon, so it might be worth a shot.
OK, bought and installed a new intake valve. The washer no longer fills when it shouldn’t, but otherwise nothing has changed. The washer simply refuses to start, with or without the door sensor shunted closed. It still reports error E6, the turbidity sensor. Would that really keep the washer from running? I’d really love some suggestions that aren’t expensive. :)
I found a $10 turbidity sensor on eBay, so I bought it and installed it. After putting the washer back together, the diagnostic still says the turbidity sensor is bad. I’m inclined to take that as a sign that it’s the control board that’s bad, which means it’s time to get a new washer. I’d love to hear a dissenting opinion.
I opened the dishwasher up again tested the voltage across the water intake valve solenoid while it’s plugged in. With the power on, there’s 120VAC across the solenoid, regardless of whether the washer is trying to start a cycle or in cancel/drain mode. There’s also 120VAC across the solenoid regardless of whether the door is open or not. (Again, I’ve thoroughly tested the door switch, and it’s behaving as expected.) The voltage for the solenoid is being driven directly by the control board, which doesn’t bode well.
The other odd thing is that even with 120VAC across the solenoid, the water intake valve is not opening; it refuses to let water through. I’m also unable to hear or feel the solenoid actuate when applying power.
It’s looking to me like the control board really has failed. In addition, the new water intake valve seems bad or maybe misinstalled. At this point, I’ve run out of rope with my wife, so we’re off to buy a new washer.