BoilerFaultCodesYour boiler has a faulty temperature sensor responsible for tracking the heat of your tap water, which usually results in inconsistent or no hot water.
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: Hot water negative temperature coefficient (NTC) fault.
What causes this fault?
This fault occurs when the sensor responsible for measuring the temperature of your hot water fails or sends an incorrect signal to the main control board. The most common reason is that the internal components of the sensor have degraded over time or developed a short circuit, meaning the boiler can no longer safely determine how hot the water is. Occasionally, this can also be caused by loose or damaged wiring connecting the sensor to the boiler's computer.
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 E321 — no call-out fees, no surprises.
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