Low
d.27 on Vaillant ecoTEC plus

This code is not actually an error, but a display setting that shows which external device or auxiliary pump is currently connected to your boiler's secondary circuit.

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.

Technical description

Function of relay 1 (multi-functional module): 1=Circulation pump, 2=External pump, 3=Cylinder charging pump, 4=Extractor hood, 5=External solenoid valve, 6=External fault message, 7=Solar pump (omitted), 8=eBUS remote control, 9=Legionella protection pump, 10=Solar valve

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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