Low
S.99 on Vaillant ecoTEC exclusive

Your boiler is currently performing an automatic internal check and is not experiencing a fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

Vaillantself-test | Self-test

Engineer required

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

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