BoilerFaultCodesYour boiler has shut down because a sensor has detected that it is getting far too hot, likely due to a circulation problem.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: CTN2 > 97°C - pump will run
What causes this fault?
This fault occurs when the internal temperature of the water exceeds 97°C, triggering a safety shutdown to prevent damage. The most common cause is a failure in the circulation pump or a blockage in the heat exchanger, which prevents the heated water from moving away from the burner quickly enough. It can also be triggered by air trapped in the system or a faulty sensor providing an incorrect high temperature reading.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on after months of inactivity, as pump components can seize during the summer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 14 — no call-out fees, no surprises.
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