Medium
FA9 on Viessmann Vitodens 025-W

Your boiler has lost its connection to your smart thermostat or external heating controller.

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

OpenTherm remote control not connected

Shared across the Vitodens 025-W, range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s 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 if your thermostat batteries need replacingEnsure your internet router and hub are switched on and connectedCheck for loose wires at the thermostat base unit if it is easily accessiblePress the reset button on the boiler control panel

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Related fault codes

F.225View →EbView →

All 24 fault codes on the Vitodens 025-W

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

F0AF0bF0CF02F03F04F05F07F08F09F10F18F30F31F38F39F51F58F59Fb0Fb8FF1FF2

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