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Viessmann 200 and 222 fault fault F2

Fixed high limit switch open (activated)

Gas boiler

What it means

Burner in fault mode due to detailed code 129: fixed high limit switch open (activated)

Likely causes

  1. Low heating system fill level
  2. Circulation pump fault
  3. Air in system
  4. Fixed high limit switch or cable fault

Where to start

  1. Check heating system fill level
  2. Check the circulation pump
  3. Bleed air from the system

The full answer, free

  • 2 more checks in order
  • How to put it right, step by step
  • The manual page for this fault (page 2), right under the answer
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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 200 and 222 fault. Check the model on the data plate before you order parts.

Other Viessmann 200 and 222 fault fault codes