Medium
D.028 on Vaillant ecoTEC Plus 832

Your boiler has detected an issue with an external accessory, such as a heating pump or an add-on control device, preventing it from communicating with the system correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Functionofext.accessoryrelay2

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 74.
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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