BoilerFaultCodesWhat the manual says
Manufacturer manualLow powers supply voltage.
From this model's manual
Verified against the Alpha/Alpha Pro Tec 24 installation & service manual, page 35.
What causes this fault?
This fault occurs when the sensor responsible for monitoring your hot water temperature sends an impossible reading to the boiler's internal computer. It is usually caused by the sensor failing internally due to age or a loose connection in the wiring that prevents the signal from reaching the control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Related fault codes
All 73 fault codes on the Pro Tec Plus
Seeing a different code? Every code this model can display, in one place.