BoilerFaultCodesVaillant L.097 Fault Code
Also written as L097 — same fault.
The Vaillant L.097 fault code means: your boiler is struggling to mix the right amount of air with the gas it uses to create a flame, which means it has safely shut itself down to prevent inefficient burning.. It appears on 3 Vaillant models in our database.
Technical description: The air ratio is too low.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Vaillant models that show the L.097 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant L.097 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026