F9 or L9 or F8 or L8 High

Ideal F9 or L9 or F8 or L8 Fault Code

Also written as F9ORL9ORF8ORL8 — same fault.

The Ideal F9 or L9 or F8 or L8 fault code means: your boiler's computer system has lost its settings or is failing to communicate, meaning the boiler cannot safely operate. because the central control unit is malfunctioning, you will currently have no heating or hot water.. It appears on 6 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 UNCONFIGURED OR FAULTY - SEE SECTION 3.19 IF FAULT PERSISTS REPLACE PCB
Typical repair cost £250-450 (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 F9 or L9 or F8 or L8 fault code

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

Source

Ideal F9 or L9 or F8 or L8 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 31 August 2026