LED 3 (B) High

Ferroli LED 3 (B) Fault Code

Also written as LED3B — same fault.

The Ferroli LED 3 (B) fault code means: your boiler is currently idle because it is not receiving a signal from your thermostat or timer to start heating.. It appears on 1 Ferroli model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Roomstat (72) or clock (62) not calling for heat
Typical repair cost £90-180 (including labour)

DIY fix possible

Check that your wall thermostat is set to a temperature higher than the current room temperature.Ensure your timer or programmer is set to an 'ON' period.Replace the batteries in your wireless room thermostat if it uses them.Check if any smart heating app linked to your boiler says the system is in 'Off' or 'Away' mode.

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Ferroli models that show the LED 3 (B) fault code

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

Source

Ferroli LED 3 (B) 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