High
C1 54 on Atag Sov.

Your boiler has detected that water is heating up too quickly or flowing in the wrong direction, often because something is blocking the circulation of water through the system.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Flow increases too fast, 3-T to large, return > supply

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

C1 05View →C1 10View →C1 18View →

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