High
d.24 on Vaillant Ecomax Condensing 600/800 series

Your boiler is signalling that the fan speed is not reaching the required level, which prevents the unit from starting the ignition process.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Not applicable in GB

From this model's manual
Verified against the Vaillant Ecomax Condensing 600 800 Series 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.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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