BoilerFaultCodesYour boiler is struggling to switch between providing hot water and heating your radiators because an internal valve is stuck or malfunctioning.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: 3-way valve
What causes this fault?
This fault occurs when the mechanical component that directs hot water between your taps and radiators becomes jammed or fails to move. It is often caused by a build-up of debris and sludge from within the heating system or a simple failure of the small motor that pushes the valve into position.
This issue is frequently noticed in autumn when homeowners turn their heating back on for the first time, as the valve may have seized after months of only providing hot water.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like T.02 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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