Bosch Logixx Dishwasher Draining, wont start cycle (not float) SGS0905AU/01

[Sambojoe]

Hi there,
I really can't work this one out!

- Bosch Logixx Dishwasher SGS0905AU/01
- Draining motor runs when any program cycle starts, but it does not stop and never fills with water
- I have checked the float, it is down, cleaned, no water present in bottom of machine either
- I have checked with multimeter the microswitches for the float and they are fine
- I have replaced the Aquastop-Valve (00267839) with new, but that didn't change anything
- If I cancel the program, either having manually added some water to machine or not, the drain motor will run, drain the machine and end the cycle as normal
- I have disassembled totally, cleaned all hoses, confirmed no kinks in water inlet hose
- I have disconnected drain hose from heat exchanger to allow drain pump to run with hose at ground level, drain pump just continued to run
- This issue occurred during a cycle, now it is constant

So all I can think is that for some reason the machine is not being triggered that the pre program drain has complete which triggers the aquastop valve, then allows water to enter the heat exchanger (skinny water reservoir) and the cycle to start.
Is there a sensor for this?

If anyone has any input I would greatly appreciate it!

Here is product part diagram - https://www.bosch-home.com.au/supportdetail/product/SGS0905/01#/Tabs=section-spareparts/

 

[Sambojoe]

Further information, not sure if this is helpful...
I located Aquasensor 00175340 that is part of the instant water heater. I can't find much information on this part, so I can only assume this is an IR sensor to detect water - unsure if relates to draining and filling or just operation of heater.
I've removed it and the housing/plug, and cleaned, but it wasn't really dirty.
I've attempted to run a washing program with the IR sensor removed (nothing blocking IR path), and after cleaning and reinstalled - but the issue remains.
I assume that this part would fail safe.
I'm not sure how to test this part, or if I can short it to think it's empty.

I am still washing dishes by hand

 

[Sambojoe]

Thank you to all that looked at my issue and used some brain power for me.
I unfortunately couldn't locate the issue, or any information online.
I binned it and purchased a SMU46KS01A to replace it.

 

[jason_guo]

i meet this problem before, it displays E15 error code. drain pump kept running long time, endless. i searched and there are many suggestion on webs. finally, there is one help that is correct; it is base trap being fill with some water by leak or condensed water from moisture. the water trigged a sensor switch to tell control board to keep running drain pump.
what i did is to flip washer toward back in some digress to flow water out. also used a dry towl to suck the rest of water. restart washer, the problem is gone!

 

[Sambojoe]

Thank you for your reply. My machine displayed no error codes. Hopefully your reply will help others with similar.