C 61 High

Atag C 61 Fault Code

Also written as C61 — same fault.

The Atag C 61 fault code means: your boiler's internal computer brain has temporarily lost its ability to talk to the control sensors and requires a manual power restart.. It appears on 1 Atag model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: No bus communication (reset only possible by power interruption)
Typical repair cost £0-180 (including labour)

DIY fix possible

Locate the main electrical power switch for your boiler (usually a fused spur switch nearby).Turn the power switch to the 'Off' position and wait for 30 seconds.Turn the power switch back to 'On' to allow the system to reboot and re-establish communication.

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Atag models that show the C 61 fault code

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

Source

Atag C 61 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 7 July 2026