B5 Low

Ideal B5 Fault Code

The Ideal B5 fault code means: your boiler is working at its higher power setting to meet a heavy demand for heating or hot water, and everything is functioning as it should.. It appears on 1 Ideal model 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: Feed to 2nd stage operating indicator from burner high fire control to boiler panel. Indicates high fire in operation.

DIY fix possible

No action is required as this is an operational status message rather than a fault.Monitor the boiler to ensure it returns to standard operation once the demand for heat reduces.

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Ideal models that show the B5 fault code

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

Source

Ideal B5 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026