How much does it cost to fix Ferroli error code LED 4: 0?

Typical repair cost for the Ferroli LED 4: 0 fault is £90-160 including labour.

LED 4: 0 High

Ferroli LED 4: 0 Fault Code

Q: What does the Ferroli LED 4: 0 fault code mean?

Your boiler has detected an issue with the sensor that monitors hot water temperature, which often means the water is getting too hot or the sensor has stopped working.

Also written as LED40 — same fault.

The Ferroli LED 4: 0 fault code means: your boiler has detected an issue with the sensor that monitors hot water temperature, which often means the water is getting too hot or the sensor has stopped working.. It appears on 2 Ferroli models in our database.

Technical description: D.H.W. sensor (42) not connected or D.H.W. temperature too high

Typical repair cost £90-160 (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 LED 4: 0 fault code

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

Source

Ferroli LED 4: 0 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