Your boiler's computer system has encountered an internal technical glitch that is preventing it from operating correctly.

Internal error.

What causes this fault?

This fault occurs when the boiler's main control board suffers a critical electronic failure, essentially losing its ability to process data or talk to the sensors. The most common reason is an electrical surge or a component failure within the circuit board's internal memory. Because the 'brain' of the boiler can no longer guarantee safe operation, it shuts the system down entirely.