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 10 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 31 August 2026