B-5 Low

Ferroli B-5 Fault Code

Also written as B5 — same fault.

The Ferroli B-5 fault code means: your boiler is currently in a brief, automatic rest period and will restart heating water once the cooling process finishes.. It appears on 2 Ferroli models 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: Waiting time still operating (max. 3 minutes)

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 B-5 fault code

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

Source

Ferroli B-5 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