F09 High

Ideal F09 Fault Code

The Ideal F09 fault code means: your boiler's internal computer has developed a fault and can no longer control the heating or hot water safely.. It appears on 3 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: PCB Fault: Replace PCB

What causes the Ideal F09 fault?

This fault occurs when the boiler's main control board experiences a critical electronics failure or a memory corruption error. The most common reason is natural wear and tear of the electrical components over time, or damage caused by an external power surge or moisture ingress.

While this fault can happen year-round, it is slightly more common during winter storms when power outages and electrical surges are more frequent.

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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Ideal models that show the F09 fault code

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

Source

Ideal F09 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