BoilerFaultCodesYour boiler has detected a faulty temperature sensor in the third heating zone, meaning it cannot accurately monitor the water returning from that specific part of your home.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Return sensor defective (zone 3)
What causes this fault?
This fault occurs when the sensor responsible for measuring the temperature of the water returning from your third heating zone fails or sends an incorrect signal to the main control board. The most common reason is a physical failure of the internal thermistor component or loose wiring connections that prevent the boiler from monitoring the system's heat levels accurately. In some cases, it can be caused by moisture ingress or a buildup of debris affecting the sensor's sensitivity.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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