Your boiler's main control computer has developed an internal electrical fault and can no longer safely operate the system.

Circuit Board Bosch, Type Heatronic II282

What causes this fault?

This fault occurs when the boiler's internal computer experiences a critical communication failure or a short circuit on the main control board. The most common reason is age-related wear to the electrical components, though occasional power surges or water leaks onto the wiring can also trigger this total system failure.