95:1 Low

Viessmann 95:1 Fault Code

Also written as 951 — same fault.

The Viessmann 95:1 fault code means: your boiler has detected an issue communicating with its remote control or internet connection module during the initial setup process.. It appears on 5 Viessmann models in our database.

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: With Vitocom 100 communication interface; automatic recognition

What causes the Viessmann 95:1 fault?

This fault occurs when the boiler's main control board fails to detect or synchronise with the plug-in internet module during its startup sequence. The most common reason is a loose internal data cable or a communication handshake error between the boiler and the Wi-Fi interface.

Typical repair cost £0-120 (including labour)

DIY fix possible

Check that your internet router is switched on and workingEnsure all cables connecting the Vitocom module to the boiler are firmly plugged inTurn the boiler power off and back on again to trigger a fresh automatic search

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Viessmann models that show the 95:1 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Viessmann 95:1 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026