Low
S.98 on Vaillant ecoTEC Pro 30

Your boiler is currently performing a brief automatic self-check and will resume normal operation as soon as the test is complete.

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

Flow/return sensor test running, heating demands are blocked.

Engineer required

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

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Related fault codes

S.96View →S.97View →

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