Your boiler is currently running a brief, automatic internal check to ensure all its systems are safe and ready to operate.

Internalautomatictestprogrammes

What causes this fault?

This code appears when the boiler’s internal computer performs a routine safety check to ensure all components are communicating correctly. It is not a breakdown, but rather a temporary pause where the system verify sensors and settings before firing up again. Unless the code remains on the screen for a long period, it simply means the boiler is double-checking its own health.