4 (Flashing Light) Low

Ferroli 4 (Flashing Light) Fault Code

Also written as 4FLASHINGLIGHT — same fault.

The Ferroli 4 (Flashing Light) fault code means: your boiler is currently idle and waiting for a signal to provide heating or hot water, so it is simply in 'standby' mode and functioning as expected.. It appears on 9 Ferroli models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Central Heating standby

DIY fix possible

Check your room thermostat is set to a higher temperature than the current room temperatureEnsure your heating programmer or timer is set to the 'on' positionCheck that the hot water tap is turned on if you are testing for hot water demand

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Ferroli models that show the 4 (Flashing Light) fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ferroli 4 (Flashing Light) fault code information on this page is sourced and cross-checked against the official Ferroli service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026