Your boiler's internal computer is having trouble communicating with one of its main control parts, meaning the system cannot run.

Module not detected.

What causes this fault?

This fault occurs when the boiler's central brain loses its physical connection with one of the primary control modules, preventing it from sending or receiving instructions. The most common reason is an electrical failure within the main circuit board or a loose internal wired connection that has deteriorated over time due to heat and vibration. Because the system can no longer verify that all safety components are connected, it shuts down immediately to prevent damage.