BoilerFaultCodesTechnical description
Flue negative temperature coefficient (NTC) thermostat fault.
What causes this fault?
This fault occurs when the boiler's control system receives an incorrect or missing signal from the sensor that monitors exhaust gas temperatures. The most common reason is that the sensor itself has developed an electrical failure or the wiring connecting it to the main control board has become loose or damaged. Because this sensor is a vital safety component that prevents the boiler from overheating internally, the system will shut down immediately to prevent damage.
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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