BoilerFaultCodesYour boiler's temperature sensor responsible for monitoring the hot water storage is faulty or has lost connection, meaning the system cannot safely heat your water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Tank (Heat Bank) NTC sensor defective.
What causes this fault?
This fault occurs when the internal sensor responsible for monitoring the temperature of your stored hot water fails to send a clear signal to the main control board. The most common reason is that the sensor has developed an internal electrical fault or its wiring has become loose or corroded over time. Because the boiler no longer knows how hot the water is, it shuts down as a safety precaution to prevent overheating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like A5 — 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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