BoilerFaultCodesAtag 50 Fault Code
The Atag 50 fault code means: your boiler has detected a problem with the sensor that manages your hot water temperature, which may result in your taps running cold or having inconsistent heat.. It appears on 7 Atag models in our database.
Technical description: Domestic hot water (DHW) sensor error
What causes the Atag 50 fault?
This fault occurs when the internal sensor responsible for monitoring your hot water temperature has failed or is sending an incorrect signal to the main control board. The most common reason is that the sensor has suffered electrical wear over time or the wiring connecting it to the boiler's computer has come loose or corroded.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →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 27 April 2026