Low
S.27 on Vaillant ecoTEC plus 637

Your boiler is currently cooling itself down by circulating water, which is a normal process and not an error.

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

Pump over run

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 637 4104465 installation & service manual, page 43.
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 occurs when the boiler has finished heating your hot water and needs to move the remaining heat away from the internal heat exchanger. It is a standard safety feature where the pump continues to run for a short period to protect the internal components from heat stress. This is part of the boiler's normal cooling cycle and does not indicate a breakdown.

Engineer required

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

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Related fault codes

All 77 fault codes on the ecoTEC plus 637

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

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