Boiler shuts down intermittently without showing an error code; may restart on its own later.

Safety first: Isolate power before checking internal connections.

• Check ventilation: Ensure the boiler cupboard or room has adequate ventilation and is not used for storage that blocks airflow.
• Inspect connectors: Gently press all plug-in connectors on the PCB, sensors, and major components to ensure they are fully seated.
• Monitor power supply: If lights flicker or other appliances reset, have an electrician check the supply for voltage drops.
• Log behavior: Note when shutdowns occur (time of day, weather, demand level) to help a technician diagnose.