Your boiler is having trouble detecting when you turn on your hot water taps, which may result in your water staying cold.
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: DHW flow sensor fault
What causes this fault?
This fault occurs when the boiler's internal computer can no longer detect the signal from the sensor that monitors water moving through the system. The most common reason is that the sensor has developed an electrical failure or the internal turbine has become stuck, meaning the boiler doesn't 'know' you have turned a tap on. In some cases, it can also be caused by loose or damaged wiring connecting the sensor to the main control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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