Makers of appliances like washing machines implement a diagnostic mode which enables manual control to command specific cycles (filling, agitating, draining, spinning). There is typically also a secret set of steps to see error codes.

Why do retailers like Krefel get that info? I have never seen a retailer who actually connects their machines to water and sewage, so it’s unclear how they use the secret modes.

In any case, they are somehow prohibited from sharing the secret info with customers -- those who actually need diagnostic control to maintain their own property.