F9 SU High

Ideal F9 SU Fault Code

Also written as F9SU — same fault.

The Ideal F9 SU fault code means: your boiler is currently stuck in its startup setup mode and needs to be properly configured before it can provide heating or hot water.. It appears on 1 Ideal model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Initial state shown during PCB configuration
Typical repair cost £100-£350 (including labour)

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 F9 SU fault code

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

Source

Ideal F9 SU 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