Low
d.71 on Vaillant ecoTEC plus 637

Your boiler is simply indicating that the heating temperature dial is currently turned to its maximum setting.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Maximum setting of heater control knob

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 637 4104465 installation & service manual, page 45.
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

Locate the radiator heating control dial on the front of your boiler panelRotate the dial slightly anti-clockwise to a lower temperature settingMonitor the display to confirm the code clears once the setting is no longer at the absolute maximum

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All 77 fault codes on the ecoTEC plus 637

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

Communication faultF.00F.01F.02F.03F.10F.11F.12F.13F.20F.22F.23F.24F.25F.26F.27F.28F.29F.32F.35F.42F.49F.52F.53F.54F.56F.57F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.76F.77F.78F.83F.84F.85F.91F.92F.93S.04S.10S.11S.14S.15S.16S.17S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.41S.42S.53S.54S.96S.97S.98

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