4 (Flashing) Low

Ferroli 4 (Flashing) Fault Code

Also written as 4FLASHING — same fault.

The Ferroli 4 (Flashing) fault code means: your boiler is working correctly and is currently in standby mode, waiting for a signal from your thermostat or hot water tap to start.. It appears on 4 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 timer or programmer is currently in an 'ON' periodTurn up the heating dial on the front of the boiler if it is set too low

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Ferroli models that show the 4 (Flashing) fault code

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

Source

Ferroli 4 (Flashing) 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