How much does it cost to fix Atag error code C1 11?

Typical repair cost for the Atag C1 11 fault is £150-300 including labour.

C1 11 High

Atag C1 11 Fault Code

Q: What does the Atag C1 11 fault code mean?

Your boiler has detected that the water inside has become dangerously hot and has shut itself down to prevent damage or safety issues.

Also written as C111 — same fault.

The Atag C1 11 fault code means: your boiler has detected that the water inside has become dangerously hot and has shut itself down to prevent damage or safety issues.. It appears on 4 Atag models in our database.

Technical description: Maximum temperature exceeded

Typical repair cost £150-300 (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 C1 11 fault code

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

A200 Repair: £150-300
Q 25CR Repair: £150-300
S 25CR Repair: £150-300
Sov. Repair: £120-350

Source

Atag C1 11 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