L9 High

Baxi L9 Fault Code

The Baxi L9 fault code means: your boiler has detected an issue with the internal ventilation system that pushes waste gases outside, so it has purposefully shut down to keep your home safe.. It appears on 1 Baxi 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: Fan Fault
Typical repair cost £180-350 (including labour)

Engineer required

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

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Baxi models that show the L9 fault code

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

Source

Baxi L9 fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026