Medium
N.317 on Vaillant ecoTEC Plus 836

Your boiler is having trouble communicating with the part that detects when you turn on a hot water tap, meaning it may fail to provide hot water 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

Interruption in the wiring harness. The signal for the volume flow sensor in the domestic hot water circuit is implausible.

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 95.
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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