Emergency
Flame On Before Gas On on Keston C30 / C35

Your boiler has detected a signal that a flame is present when it shouldn't be, which is a safety lockout preventing it from lighting.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

False flame detected before gas valve operation

From this model's manual
Verified against the Keston C30 C35 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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