Viessmann Vitodens 100-W fault E12

WiFi connection to server could not be established

Gas boiler

What it means

Displayed when the integrated WiFi communication module connects to the home network but cannot reach the manufacturer's server.

Likely causes

  1. Short circuit, collector temperature sensor
  2. Server temporarily unavailable
  3. Internet connectivity issue beyond the local router

Where to start

  1. Check collector temperature sensor
  2. Measure voltage at sensor input on electronics module (ADIO)
  3. Re-establish the connection at a later time

The full answer, free

  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 36), right under the answer

Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.

From the Viessmann manual for the Vitodens 100-W. Check the model on the data plate before you order parts.

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