Your boiler's main control panel is having trouble talking to the internal computer, meaning you cannot adjust settings or operate the unit effectively.

Control mode - Communication fault – programming unit (internal)

What causes this fault?

This fault occurs when the data link between the boiler's main display screen and its internal control board is interrupted. The most common reason is a loose internal connection cable or a electronic component failure within the programming unit itself. Because these two parts can no longer 'talk' to each other, the boiler cannot receive commands to provide heating or hot water.