BoilerFaultCodesTechnical description
Low loss header temperature sensor faulty – check the sensor port or check the differential sensor for incorrect installation position or breakage
What causes this fault?
This fault occurs when the boiler's control system detects a discrepancy between the water temperature sensors, often because the sensor monitoring the external mixing point is giving an impossible reading. The most common reasons are a physical failure of the sensor itself, an electrical fault in the connecting wires, or the sensor being installed in the wrong location during a complex system setup.
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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