Low
d.13 on Vaillant Home System

Your boiler is simply showing whether the water pump for your hot water is currently running or not; this is a status update rather than a fault.

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 of the hot water circuit's circulation pump: off/on

From this model's manual
Verified against the Vaillant Home System 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.

DIY fix possible

Check your hot water timer or thermostat settings to see if the pump is scheduled to be onNo action is required as this is an informational status code, not an error

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