BoilerFaultCodesAlpha 0E45 Fault Code
The Alpha 0E45 fault code means: your boiler has detected an issue with the sensor that monitors the temperature of the gases leaving your system, which is preventing it from firing up safely.. It appears on 3 Alpha models in our database.
Technical description: Flue sensor short circuit.
What causes the Alpha 0E45 fault?
This fault occurs when the sensor responsible for measuring the temperature of the exhaust gases sends an incorrect electrical signal to the boiler's brain. The most common reason is that the sensor has suffered an internal electrical failure or the connecting wires have become damaged or loose. Because the boiler can no longer safely monitor heat levels in the flue, it shuts down immediately to prevent overheating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Alpha models that show the 0E45 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha 0E45 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026