Karen, have you read this ? https://www.siemens-home.bsh-group.com/uk/customer-service/support/problems/dishcare/dishcare-error-codes#/Togglebox=5409380-5407991-1/

mine is about 6 years old and every couple of months I get e22, which is supposed to be something to do with the dirty water sump. I have opened that up (just the grey plastic tube and grill on bottom) and cleaned it up but then it will return a bit later. I may need to look at getting the pump change but for now this interim fix seems to work