11 High

Atmos 11 Fault Code

The Atmos 11 fault code means: your boiler has detected a problem with one of its internal temperature sensors, which means it cannot safely measure the heat of the water and has stopped working as a precaution.. It appears on 4 Atmos 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: Sensor fault S1 — check wires for breaks; replace S1
Typical repair cost £120-£190 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Atmos models that show the 11 fault code

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

Source

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

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026