Technical description
Short circuit - flow-NTC (<130°C) | NTC-plug shorted to casing, NTC defective
What causes this fault?
This fault occurs when the boiler's control board receives an impossible electrical reading from the sensor that monitors cooled water returning from your radiators. The most common reason is that the sensor has developed an internal electrical short or the wiring connecting it to the main board has become loose or damaged. Because the boiler can no longer safely track the water temperature, it shuts down to prevent overheating.
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.