Your boiler is experiencing a communication or configuration error between internal electronic boards that prevents it from starting correctly.

Temporary fault code (Refer to section 7.10)

What causes this fault?

This fault occurs when the boiler's internal electronic brains stop speaking to each other. The most common reason is a communication failure between the main control board and the display panel, often caused by a loose wire or a failing circuit component. Because the two boards cannot confirm the boiler's safety settings, the system shuts down as a precaution.