BoilerFaultCodesVaillant Burner lock out indicator Fault Code
Also written as BURNERLOCKOUTINDICATOR — same fault.
The Vaillant Burner lock out indicator fault code means: your boiler has stopped trying to light because it cannot detect a flame or is not receiving gas, leaving you without heating or hot water.. It appears on 2 Vaillant models in our database.
Technical description: The burner lock out indicator will illuminate. This usually means that the gas supply is turned off or has not been purged of air.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Vaillant models that show the Burner lock out indicator fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant Burner lock out indicator 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 27 April 2026