Low
S.1 on Vaillant ecoTEC exclusive

Your boiler is currently preparing to start the fan as part of its normal ignition process.

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

Status indicator during start-up/heat demand sequence

Shared across the ecoTEC exclusive range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This status code appears when the boiler's internal computer sends a signal to the fan to begin spinning before ignition. It is a natural part of the start-up sequence where the fan clears the combustion chamber and prepares the correct air-to-gas ratio. If the code stays on screen for a long time, it usually means the fan is struggling to reach the required speed or is not communicating back to the main board.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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Related fault codes

S.2View →S.3View →F.32View →

All 71 fault codes on the ecoTEC exclusive

Seeing a different code? Every code this model can display, in one place.

conF.0F.1F.10F.11F.13F.20F.22F.23F.24F.25F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.70F.71F.72F.73F.74F.75F.76F.77P.0P.1P.2P.5P.6S.0S.2S.3S.4S.5S.6S.7S.8S.10S.11S.13S.14S.15S.16S.17S.21S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.36S.41S.42S.53S.54S.96S.97S.98SEr

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