LED 4 green (0) [DHW mode] High

Ferroli LED 4 green (0) [DHW mode] Fault Code

Also written as LED4GREEN0DHWMODE — same fault.

The Ferroli LED 4 green (0) [DHW mode] fault code means: your boiler has stopped producing hot water because it believes the internal temperature sensor is either disconnected or reading an dangerously high temperature.. It appears on 2 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: D.H.W. sensor (42) not connected or D.H.W. temperature too high
Typical repair cost £120-200 (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 green (0) [DHW mode] fault code

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

Source

Ferroli LED 4 green (0) [DHW mode] 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