High
12 on Alpha H25 Xtraflame

Your boiler has lost the ability to accurately measure the temperature of your hot water tank, so it has stopped heating it to prevent overheating.

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

Cylinder sensor fault (InTec S and FlowSmart only) - Incorrect cylinder sensor resistance

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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