Your boiler has detected an internal communication or unexpected component fault and has stopped working as a safety precaution.

Miscellaneous error.

What causes this fault?

This fault occurs when the boiler's internal computer is unable to communicate with its electrical components or receives an unexpected signal that doesn't match normal operation. It is often caused by a malfunctioning main circuit board or a loose connection in the internal wiring harness that prevents instructions from being sent correctly. In some cases, a failing gas valve can also trigger this 'miscellaneous' error by sending unrecognised feedback to the control system.