BoilerFaultCodesTechnical description
Safety temperature limiter by NTC activated. Flow-NTC not correctly thermal-connected or defective; appliance does not shut down
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the water temperature has risen too quickly or exceeded a safe limit, triggering an emergency shutdown to prevent damage. The most common cause is a lack of water circulation, often due to a seized pump, a blockage in the pipework, or air trapped within the heat exchanger.
This fault is more common when the heating is first turned on after summer, as pump components can seize up during long periods of inactivity.
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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