High
Green/Red flashing on Grant Vortex 15-20

Your boiler has detected light inside the combustion chamber when it should be dark, causing it to lock itself out as a safety precaution.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Burner lockout occurs if extraneous light or flame is detected for 25 seconds during pre-purge

Engineer required

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

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Related fault codes

LockoutView →

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