Your boiler is struggling to accurately measure the temperature of your hot water, which usually means your taps will only run cold.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: DHW NTC Sensor c/w cable 1.25 m
What causes this fault?
This fault occurs when the internal sensor responsible for monitoring your hot water temperature fails or sends an unreadable signal to the main control board. The most common reason is that the sensor has physically degraded over time or a loose connection in the wiring harness is preventing the boiler from knowing how hot the water is. To prevent overheating, the boiler will stop heating your water entirely until the part is replaced.
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.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E83484 — no call-out fees, no surprises.
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Potterton Powermax HE 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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