BoilerFaultCodesKeston Enn Fault Code
Also written as ENN — same fault.
The Keston Enn fault code means: your boiler has encountered a critical system error and has shut itself down as a safety precaution.. It appears on 8 Keston models in our database.
Technical description: Fault causing a boiler shutdown
What causes the Keston Enn fault?
This fault occurs when the boiler's internal computer experiences a major communication failure or a critical hardware error. It typically happens because the main control board can no longer safely monitor the unit's operation, leading to an immediate shutdown to prevent damage. The most common trigger is a sudden electrical surge or a terminal failure of the electronic components inside the boiler.
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 Enn fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston Enn 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