Bosch SHX7ER55UC dishwasher stopping mid cycle

[DKNJ]

Bosch 800 Plus series SHX7ER55UC stops mid cycle. The display remains lit showing 0:00 (normally it would be off at the end of a cycle). This happens anywhere from a minute or two after starting to an hour or more into the cycle, often in the middle of spray action and seeming not to be at a cycle change point.

Diagnostic self-test usually exits with 0 on the display but sometimes it stops after step S:03 and sometimes it gets all the way to step S:22. In one instance the tub overflowed and water started spilling onto the floor without displaying an error code at step S:07. When I installed the new control board the machine started up in self-test mode and quickly displayed E:08 but I haven't been able to reproduce the error since that initial startup routine.

I have replaced:
Turbidity sensor
Regeneration valve
Control board

I have tested the heating pump & NTC resistances, all are within spec according to the service manual

The drain pump is operating as expected. The drain and hoses are clear.

The bottom is dry.

I have reduced the home's hot water temperature to 130 F, it was accidentally set to 145 F after a recent hot water tank replacement.

The rinse aid tank is full of water but I haven't changed the dispenser yet because I'm trying to make sure the problem of unexpected stopping is repairable first. The soap compartment still opens correctly.

I've searched for other reports of this condition but didn't find anything quite like it. Any suggestions where to go next?

[DKNJ]

I may have identified the problem.  

There's a large, semi-transparent water inlet chamber on the left hand side of the dishwasher. An impeller inside that unit that looks like a little paddle wheel is supposed to measure the water flow. I can see it spinning freely at first but then it starts to slow down and stick about a minute into the fill operation, eventually starting and stopping intermittently while water continues to fill.

I think if the impeller doesn't spin smoothly then the flow rate is measured incorrectly and the dishwasher doesn't know when it's full, until it presumably hits a safety switch (which I don't see).

I don't know why the machine just stops with 0:00 on the display and beeps 5 times as if the cycle is finished instead of throwing an error code, though. Shouldn't it display E:14 in that situation?

Can anyone confirm that the impeller should function as I described and that it's not normal for it to slow down while water is filling?

[Budget Appliance Repair]

Pretty sure you have found your problem.

Anytime water is flowing into that side chamber and past the paddle wheel the paddle wheel should be turning smoothly - operates just as you describe.

If water is flowing and the paddle wheel isn't turning, then it doesn't know the water is flowing and can't measure the amount of water that has entered correctly.

[DKNJ]

Thanks Willie. I have already ordered the part and I hope that will finally resolve the problem.  It's been a bear to diagnose because there's no error code and the impeller wheel only stops intermittently, so I had to be looking at it at just the right time to finally see it happening.