BoilerFaultCodesYour boiler has detected a problem with the sensor that monitors your hot water temperature or a switch that controls water flow, which usually means your hot water will stop working properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Domestic hot water sensor error – could be a heating flow switch error)
What causes this fault?
This fault occurs when the boiler's control board receives a signal that is outside of the normal range from the hot water temperature sensor or the flow switch. This is usually caused by the internal electrical components wearing out over time or a loose connection in the wiring that prevents the boiler from accurately monitoring the water temperature.
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 E164 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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