BoilerFaultCodesIdeal 401 Fault Code
The Ideal 401 fault code means: your boiler's internal computer brain has experienced a malfunction and can no longer communicate with the heating system.. It appears on 2 Ideal models in our database.
Technical description: internal failure - electronic
What causes the Ideal 401 fault?
This fault occurs when the boiler's central control board suffers a hardware failure, meaning it can no longer process instructions or monitor safety sensors. The most common reason is an electrical short-circuit or component degradation on the circuit board that prevents it from 'thinking' correctly. Because the control board is the brain of the appliance, it shuts down completely for safety when it detects this internal error.
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 401 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 401 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