I3 Low

Ideal I3 Fault Code

The Ideal I3 fault code means: your boiler is receiving power correctly, but the system has not detected a fault or specific issue at this moment.. It appears on 3 Ideal models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Mains electricity ON.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Ideal models that show the I3 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ideal I3 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 7 July 2026