BoilerFaultCodesTechnical description
Differential water flow switch is still closed
What causes this fault?
This fault occurs when the boiler's internal sensors believe water is still moving through the system even after the pump has been told to stop. This is usually caused by a mechanical sensor becoming stuck in the 'on' position due to debris in the system water, or a pump that is failing to switch off correctly. It acts as a safety measure to prevent the boiler from firing when it cannot accurately control the flow of water.
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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