BoilerFaultCodesAtag 10 Fault Code
The Atag 10 fault code means: your boiler has lost communication with its outdoor temperature sensor, which means the system may not be able to adjust its heating efficiency based on the weather outside.. It appears on 9 Atag models in our database.
Technical description: Outside sensor error (e.g. open, short circuit, out of range)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Atag models that show the 10 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Atag 10 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