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 error
What causes this fault?
This fault occurs when the boiler's control system receives an incorrect or missing signal from the sensor located in the exhaust flue. The most common reason is that the sensor itself has failed due to age or heat exposure, though it can also be triggered by a loose electrical connection or moisture affecting the internal wiring.
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 E28 — no call-out fees, no surprises.
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