BoilerFaultCodesAtag 50 Fault Code
The Atag 50 fault code means: your boiler has detected a problem with the sensor that manages your hot water, which means it cannot accurately tell if the water is at the right temperature.. It appears on 8 Atag models in our database.
Technical description: T3 (DHW) 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 50 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Atag 50 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