LED 4 (Flashing) Low

Ferroli LED 4 (Flashing) Fault Code

Also written as LED4FLASHING — same fault.

The Ferroli LED 4 (Flashing) fault code means: your boiler is currently in standby mode for the central heating and is waiting for a signal from your thermostat to turn on.. It appears on 1 Ferroli model 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
Typical repair cost £0-60 (including labour)

DIY fix possible

Check that your room thermostat is turned up higher than the current room temperature.Ensure your heating programmer or timer is set to an 'ON' period.Replace the batteries in your wireless thermostat if the display is faint or blank.

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

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

Source

Ferroli LED 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 7 July 2026