Medium
S.23 on Vaillant ecoTEC Pro 30

Your boiler is currently trying to light up to heat your hot water, but hasn't yet successfully started the process.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

DHW mode: Ignition

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.23View →F.28View →F.29View →

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