Low
D.023 on Vaillant ecoTEC pro

Your boiler is currently performing a routine check to ensure there is enough water flowing through the heating system.

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

Heating mode status

Shared across the ecoTEC pro 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.

DIY fix possible

Check your boiler's pressure gauge to ensure it is between 1 and 1.5 barIf the pressure is low, locate the filling loop and add water until the needle reaches the green zoneWait a few minutes for the boiler to complete its internal check and return to normal operation

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Related fault codes

All 157 fault codes on the ecoTEC pro

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

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