LED4 flashing High

Ferroli LED4 flashing Fault Code

Also written as LED4FLASHING — same fault.

The Ferroli LED4 flashing fault code means: your boiler is struggling to detect water moving through the system, which prevents it from safely firing up to heat your home or provide hot water.. It appears on 7 Ferroli models 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: Flow Sensor / main board / pump check
Typical repair cost £150-300 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Ferroli models that show the LED4 flashing fault code

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

Source

Ferroli LED4 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