BoilerFaultCodesAtag 111 Fault Code
The Atag 111 fault code means: your boiler has shut down because the internal water temperature has become too high, often caused by a lack of water flow or a circulation error.. It appears on 3 Atag models in our database.
Technical description: Maximum temperature exceeded
DIY fix possible
Check that your boiler pressure is between 1.0 and 1.5 barEnsure all radiator valves are fully open to allow water flowCheck for any frozen external condensate pipes if it is winterTry resetting the boiler via the 'R' or reset button
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Atag models that show the 111 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Atag 111 fault code information on this page is sourced and cross-checked against the official Atag service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026