BoilerFaultCodesUnical 55 Fault Code
The Unical 55 fault code means: your boiler has lost the internal settings required to balance its gas and air mixture, meaning it cannot safely start up or heat your home.. It appears on 2 Unical models in our database.
Technical description: No Calibration
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 55 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Unical 55 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 7 July 2026