BoilerFaultCodesTechnical description
Sensor fault S1
What causes this fault?
This fault occurs when the boiler's main flow sensor, which monitors the temperature of the water leaving the heat exchanger, fails to provide a consistent or logical reading. The most common reason is that the internal electrical component of the sensor has worn out or developed a short circuit, preventing the control board from knowing if the water is at a safe temperature.
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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