Low
S.029 on Vaillant ecoTEC plus System

Your boiler is simply performing a quick, automatic self-check to ensure its internal sensors remain accurate while heating up your hot water cylinder.

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.

What the manual says

Manufacturer manual

The domestic hot water cylinder charging is active and the unit carries out an automatic drift adaptation of the ionisation electrode in order to offset the ageing of the electrode.

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

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

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Related fault codes

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