BoilerFaultCodesKeston E45 Fault Code
The Keston E45 fault code means: your boiler has detected an electrical fault with the sensor that monitors exhaust gases, causing the system to shut down for safety.. It appears on 9 Keston models in our database.
Technical description: Flue sensor short circuit – check connections to flue sensor
What causes the Keston E45 fault?
This fault occurs when the electrical signal from the exhaust gas sensor becomes interrupted, usually because the component has failed internally or the wiring has become damaged. The sensor is designed to monitor the temperature of the fumes leaving your home, and if it detects an electrical short, the boiler will shut down immediately to prevent potential overheating or safety risks.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Keston models that show the E45 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston E45 fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026