Programme does not end

Electrolux 91153921500 / Model ESL5205LO. Programme does not finish and can run for hours, water does not drain, issue on eco wash and normal wash. To finish programme and drain water 30min programme needs to be selected. Does not happen all the time maybe every 4 or 5 washes. Tried dishwasher cleaners and cleaned filters. Checked water inlet and drain hose. Thinking temp/turbidity sensor which would be worthwhile to repair, or motherboard fault which is uneconomical. If temp/turbidity sensor where is the located?