Low
S.02 on Vaillant Home Combi

Your boiler is simply preparing the internal water pump before it starts the heating process, which is a normal part of its operation.

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

Heatingmode:Pumppre-run

From this model's manual
Verified against the Vaillant Home Combi installation & service manual, page 34.
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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