Low
S.30 on Vaillant ecoTEC plus 637 H system A VU GB 376/5-5 A

Your boiler is temporarily paused because your wall thermostat or heating controller is telling it not to send heat to your radiators.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Room thermostat (RT) is blocking heating mode

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 832 Lpg Vuw Gb 326 5 5 4704459 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.

DIY fix possible

Check your wireless or wired room thermostat to ensure it is switched on and calling for heat.Turn the target temperature up higher than the current room temperature to see if the boiler fires up.Replace the batteries in your wireless room thermostat if it has a low battery warning.

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Avoid the next call-out bill

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Related fault codes

All 94 fault codes on the ecoTEC plus 637 H system A VU GB 376/5-5 A

Seeing a different code? Every code this model can display, in one place.

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