How much does it cost to fix Atag error code C14?

Typical repair cost for the Atag C14 fault is £120-200 including labour.

C14 High

Atag C14 Fault Code

Q: What does the Atag C14 fault code mean?

Your boiler has detected that the water trap responsible for disposing of condensation is potentially blocked or not draining correctly, causing it to shut down to prevent internal water damage.

The Atag C14 fault code means: your boiler has detected that the water trap responsible for disposing of condensation is potentially blocked or not draining correctly, causing it to shut down to prevent internal water damage.. It appears on 1 Atag model in our database.

Technical description: Siphon sensor fault

Typical repair cost £120-200 (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 C14 fault code

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

Premier Repair: £120-200

Source

Atag C14 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