BoilerFaultCodesYour boiler's temperature sensor has encountered a technical glitch, meaning the system cannot accurately monitor the heat of the water it is pumping around your radiators.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Central Heating NTC Fault
What causes this fault?
This fault occurs when the internal thermistor, which monitors the temperature of the water leaving the boiler, sends an incorrect signal or stops communicating entirely. The most common reason is that the sensor has degraded over time due to constant heating and cooling, or the electrical wiring connecting it to the main control board has developed a loose connection.
This fault is slightly more common in winter when the boiler is running at higher temperatures for longer periods, putting more thermal stress on the sensor.
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 E20 — no call-out fees, no surprises.
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