BoilerFaultCodesWhat the manual says
Manufacturer manualOutdoor Unit, Air to Refrigerant Heat Exchanger Outlet Thermistor (T3) Error
What causes this fault?
This fault occurs when the heat pump's control system loses the ability to accurately read the temperature of the air as it leaves the outdoor unit. The most common reason is that the sensor has developed an internal electrical failure or the wiring connecting it to the main control board has become loose or damaged.
This fault can be more frequent during periods of heavy frost or high humidity, as ice build-up on the outdoor unit can sometimes physically stress the sensor or its wiring.
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.
Avoid the next call-out bill
A cover plan would handle faults like 9.1.8: no call-out fees, no surprise bills.
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