Low
d.00 on Vaillant ecoTEC sustain

Your boiler is simply displaying a status message telling you it is automatically adjusting its power output to best heat your home, rather than indicating 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

Heating maximum output: The maximum heating output varies depending on the product. Automatic: Unit automatically adjusts the maximum output to the current system demand

From this model's manual
Verified against the Vaillant Ecotec Sustain installation & service manual, page 46.
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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