F9 High

Ideal F9 Fault Code

The Ideal F9 fault code means: your boiler's internal computer has forgotten its settings or has developed a technical communication error, meaning it cannot safely control the heating process.. It appears on 14 Ideal models 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: Printed circuit board (PCB) unconfigured or fault

What causes the Ideal F9 fault?

This fault occurs when the boiler's central control board loses its identity or suffers a data communication failure, preventing it from managing the gas valve and pumps. The most common reason is a hardware failure within the motherboard or a missing configuration chip, which acts like a memory card telling the boiler exactly which model it is. It can also be triggered by a sudden power surge or electrical interference that corrupts the board's stored settings.

Typical repair cost £280-450 (including labour)

Engineer required

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

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Avoid the next call-out bill

A cover plan would handle faults like F9: no call-out fees, no surprise bills.

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Ideal models that show the F9 fault code

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

Source

Ideal F9 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