BoilerFaultCodesIdeal J45 Fault Code
The Ideal J45 fault code means: your boiler has stopped working because it detects that the internal fan is the incorrect model for this specific unit.. It appears on 1 Ideal model in our database.
Technical description: Wrong Fan Motor Fitted
What causes the Ideal J45 fault?
This fault occurs when the boiler's control board detects that the installed fan is not communicating correctly or is incompatible with this specific model's software. It is most commonly caused by a technician installing the wrong replacement part or a communication error between the main circuit board and the fan motor.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Search the official register for a qualified engineer in your area.
Gas Safe Register →Ideal models that show the J45 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal J45 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026