BoilerFaultCodesKeston E07 Fault Code
The Keston E07 fault code means: your boiler has shut down because the internal exhaust gases are getting too hot, which is usually caused by a circulation problem or a buildup of debris inside the main heating component.. It appears on 9 Keston models in our database.
Technical description: Flue overheat - check combustion and flue temperature vs. return temperature (Installer numbers 7 and 3 above). The flue temperature should be no more than 10C above return temperature. Possible heat exchanger fault
What causes the Keston E07 fault?
This fault occurs when the internal temperature of the exhaust gases becomes dangerously high, triggering a safety shutdown to protect the appliance. The most common reason is that heat isn't being transferred effectively into your radiators, often due to a buildup of dirt or debris inside the main heat exchanger. It can also be caused by a lack of proper water flow through the boiler, which prevents the system from cooling itself down while firing.
This fault is more common in the autumn or winter when the heating is first turned back on, as stagnant sludge in the system can shift and block the narrow channels of the heat exchanger.
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 E07 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston E07 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