BoilerFaultCodesKeston Flame On Before Gas Valve On Fault Code
Also written as FLAMEONBEFOREGASVALVEON — same fault.
The Keston Flame On Before Gas Valve On fault code means: your boiler's safety sensor thinks a flame is already burning before it has even turned the gas on, causing the system to shut down for safety.. It appears on 1 Keston model in our database.
Technical description: Flame detected before the gas valve is energized. Checks: internal boiler wiring integrity and electrode condition.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Keston models that show the Flame On Before Gas Valve On fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston Flame On Before Gas Valve On fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026