BoilerFaultCodesYour boiler's hot water sensor has failed or has a broken connection, meaning you likely won't have any hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The hot water negative thermistor coefficient (NTC) sensor is defective – the hot water sensor or connecting leads need checking.
What causes this fault?
This fault occurs when the boiler's internal computer loses communication with the sensor responsible for monitoring hot water temperature. The most common reason is that the sensor has physically failed due to age or internal wear, though it can also be triggered by loose or corroded electrical wiring connecting the sensor to the main control board.
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 A7 — no call-out fees, no surprises.
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Worcester Bosch CDi Classic is discontinued — time for a new one?
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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