BoilerFaultCodesIdeal L45 Fault Code
The Ideal L45 fault code means: your boiler has identified that the internal fan is incompatible or incorrectly configured, causing the system to shut down for safety.. It appears on 1 Ideal model in our database.
Technical description: Wrong Fan Fitted
What causes the Ideal L45 fault?
This fault occurs when the boiler's control chip fails to recognize the specific fan installed in the unit. The most common reason is a communication error between the fan and the main circuit board, often caused by the wrong part being installed during a repair or a software mismatch on the board itself.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the L45 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal L45 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