BoilerFaultCodesTechnical description
Sensor fault S1
What causes this fault?
This fault occurs when the boiler's main flow temperature sensor sends an incorrect or garbled signal to the control board, suggesting the sensor has failed or become disconnected. The most common reason is that the internal components of the sensor have worn out over time, or the electrical wiring connecting it to the brain of the boiler has developed a loose connection.
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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