BoilerFaultCodesUnical 11 Fault Code
The Unical 11 fault code means: your boiler is locking out because it thinks a flame is present inside before it has even tried to ignite.. It appears on 2 Unical models in our database.
Technical description: PARASITE FLAME Flame detected upon ignition. Check the wiring of the Ign/Det. electrode and remove any oxidation. Check for humidity between drain wire and ceramic, if necessary, replace the electrode, press the unblock key, if the anomaly persists, replace the electrode (4).
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Unical models that show the 11 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Unical 11 fault code information on this page is sourced and cross-checked against the official Unical service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026