BoilerFaultCodesYour boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flue thermistor fault
What causes this fault?
This fault occurs when the sensor responsible for measuring the heat of the gases leaving your chimney sends an incorrect or missing signal to the boiler's computer. The most common reason is that the sensor itself has worn out or suffered heat damage, though it can also be caused by loose electrical connections or a blockage in the flue system. For safety, the boiler shuts down to prevent the system from overheating or releasing dangerous fumes.
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 E3 — 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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