Medium
D.016 on Vaillant ecoTEC plus Combi

Your boiler is failing to detect a signal from your room thermostat, meaning it doesn't know when to turn the heating on or off.

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

Roomthermostatstatus(24V)

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 73.
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

Check if your room thermostat batteries are flat and replace them if necessaryEnsure your thermostat is switched on and showing a displayCheck for any loose wires or visible damage at the thermostat or the boiler connection point

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