Viessmann Vitodens 100-W fault 375

Ionisation current calibration not performed

Gas boiler

What it means

Burner restarts. Performing ionisation current calibration: Calibration not performed. Minimum value or termination criterion not reached.

Likely causes

  1. Faulty ionisation electrode or connecting cable
  2. Loose plug-in connections
  3. Flue gas recirculation issue
  4. Condensate backup in system
  5. Contamination at gas solenoid valve inlet and inlet strainer
  6. Deposits on electrodes from foreign bodies in combustion air (laundry detergents, cleaning agents, toiletries, ventilation air supply/chimney deposits)

Where to start

  1. Check ionisation electrode and connecting cable
  2. Check plug-in connections for loose contacts
  3. Check flue system; remove flue gas recirculation if necessary

The full answer, free

  • 15 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 79), 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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