How much does it cost to fix Atag error code F1?

Typical repair cost for the Atag F1 fault is £0-80 including labour.

F1 Low

Atag F1 Fault Code

Q: What does the Atag F1 fault code mean?

Your boiler is displaying an advisory message indicating that specific chemical protection or anti-freeze has been added to the system water, rather than reporting an actual breakdown.

The Atag F1 fault code means: your boiler is displaying an advisory message indicating that specific chemical protection or anti-freeze has been added to the system water, rather than reporting an actual breakdown.. It appears on 3 Atag models in our database.

Technical description: Anti-freeze in combination with protector (Fernox F1 / Alphi 11)

Typical repair cost £0-80 (including labour)

DIY fix possible

Press the 'Reset' button on the display panel to clear the notification.Check your boiler service records or any stickers nearby to confirm chemical levels were recently checked.Monitor the boiler for any other actual fault codes if the heating stops working.

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Atag models that show the F1 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Atag F1 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