Medium
D.016 on Vaillant ecoTEC Pro 30

Your boiler is struggling to detect the signal from your wall-mounted thermostat, so it has stopped heating your home as a safety precaution.

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

24V DC room thermostat open/closed

From this model's manual
Verified against the Vaillant Ecotec Pro 30 installation & service manual, page 31.
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 your room thermostat to ensure the batteries are fresh and the display is active.Verify that the wires connecting your thermostat to the boiler are firmly secured and undamaged.Restart your boiler using the reset button or by turning the power off at the fused spur for 30 seconds.

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