S.11 Low

Heatline S.11 Fault Code

Also written as S11 — same fault.

The Heatline S.11 fault code means: your boiler is currently preparing to ignite, but the internal fan is checking its position before the system starts burning fuel.. It appears on 8 Heatline 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: Pre-run fan

DIY fix possible

No action required; this is a normal status messageWait for the boiler to complete its pre-ignition checksMonitor the display to see if it progresses to a heating or hot water symbol

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Heatline models that show the S.11 fault code

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

Source

Heatline S.11 fault code information on this page is sourced and cross-checked against the official Heatline service / installation manuals for each affected model.

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