Low
S.25 on Vaillant ecoTEC exclusive

Your boiler is currently just finishing its standard cooling-down process after heating your water and is not experiencing a fault.

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

DHWmode:Pump/fanoverrun

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 occurs when the boiler's internal computer is verifying that the pump is moving enough water and the fan is spinning at the right speed before ignition. It is essentially a safety check to ensure the heat exchanger won't overheat once the flame starts. If the display stays on this code for a long time, it usually means the pump is struggling to move water or a sensor is providing an inaccurate reading.

Engineer required

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

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Avoid the next call-out bill

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Related fault codes

All 71 fault codes on the ecoTEC exclusive

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

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