High
F.27 on Vaillant aquaPLUS

Your boiler has detected a false flame signal or a communication error between the gas valve and the control board, preventing it from firing up safely.

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

No demand to gas valve | Electronic board defective; Gas valve defective

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

F.28View →F.29View →F.62View →

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