BoilerFaultCodesYour boiler's internal temperature sensor has developed a fault, meaning the system cannot correctly monitor the heat of your radiators and has shut down as a precaution.
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 negative temperature coefficient (NTC) thermostat fault.
What causes this fault?
This fault occurs when the sensor responsible for monitoring the water temperature in your radiators stops sending a reliable signal to the boiler's control board. The most common reason is that the sensor has physically burnt out or degraded over time, though loose or corroded wiring connections can also disrupt the electrical circuit.
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 E20 — 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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