How much does it cost to fix Atag error code Error 12?

Typical repair cost for the Atag Error 12 fault is £120-220 including labour.

Error 12 High

Atag Error 12 Fault Code

Q: What does the Atag Error 12 fault code mean?

Your boiler has stopped working because a small internal fuse that protects its main control system has blown, cutting off the power needed for it to operate.

Also written as ERROR12 — same fault.

The Atag Error 12 fault code means: your boiler has stopped working because a small internal fuse that protects its main control system has blown, cutting off the power needed for it to operate.. It appears on 8 Atag models in our database.

Technical description: fuse 24 volt/3AT faulty

Typical repair cost £120-220 (including labour)

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 Error 12 fault code

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

Source

Atag Error 12 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