BoilerFaultCodesIdeal 404 Fault Code
The Ideal 404 fault code means: your boiler has experienced a fundamental software or memory error that has caused it to shut down securely for safety.. It appears on 2 Ideal models in our database.
Technical description: Non-volatile lockout
What causes the Ideal 404 fault?
This fault occurs when the boiler's internal memory experiences a critical failure, meaning the control board can no longer read or store the essential settings needed to run safely. It is usually caused by a physical hardware malfunction within the circuitry or an electrical surge that has corrupted the software components. Because the 'brain' of the boiler can no longer verify its own safety checks, it enters a permanent shutdown to prevent any unpredictable behavior.
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 404 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 404 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