We know its nothing to do with the metering or level device, as you have disconected this and it does the same.
You have replaced the inlet valve, so we know its not that ( unless you have had reduced water pressure recently, as this could cause this)
Unfortunately this just leaves the main control board.
There is no way to test this at home, so it would have to be on a try and see basis, which is not ideal, sorry.
I cant tell you the exact price without the model number as there are so many of these Bosch models . What I can say is that it would be between £100 and £200 for the part !!
Depending on the age, you may feel it better to put the money toward a new machine
Sorry its not great news
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