BoilerFaultCodesAlpha d11 Fault Code
Also written as D11 — same fault.
The Alpha d11 fault code means: your boiler's electronic control system is showing an undefined status, which typically means the internal computer is failing to communicate correctly.. It appears on 2 Alpha models in our database.
Technical description: Not used
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Alpha models that show the d11 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha d11 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 7 July 2026