Low
d.25 on Vaillant Thermocompact

This code is simply an indicator confirming whether your boiler's 'warm start' feature, which keeps a small amount of water pre-heated for faster taps, is currently switched on or off.

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

Warmstart status (turboMAX plus) 1 = ON; 0 = OFF

From this model's manual
Verified against the Vaillant Turbomax Plus 824 828e installation & service manual, page 39.
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

Locate the 'eco' or 'warmstart' button on your boiler control panel.Press the button to toggle the setting between 0 (Off) and 1 (On) based on your preference.Confirm the status code changes on the display to match your chosen setting.

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