F21
V-ZUG Pyrolytic Temperature or Safety System Fault

Pyrolytic self-cleaning does not start or aborts with F21; door may lock then unlock.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Faulty high-temperature NTC sensor, Defective pyrolytic safety thermostat, Cooling fan not reaching required speed, Door lock not confirmed closed

How to Fix / Troubleshooting

Safety first: Ensure the oven is cool and disconnected from mains before inspection.

Step-by-step checks:

  • Check door closure: Make sure the door closes fully and the seal is intact. Clean any debris from the door latch area.
  • Test cooling fan: Start a normal baking program and verify that the cooling fan runs strongly. If weak or not running, replace the cooling fan before attempting pyrolysis.
  • Inspect high-temp sensor: Locate the pyrolytic NTC sensor (often separate from the normal sensor) and check its wiring and resistance according to service data.
  • Check safety thermostat: Test continuity of the pyrolytic safety thermostat. If open and non-resettable, replace it with the correct V-ZUG part.

When to call a technician: Pyrolytic systems operate at very high temperatures; if F21 persists, have an authorized technician diagnose the safety chain.

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Repair Difficulty

Professional Required 5/5

Required Part

Pyrolytic Safety Thermostat / High-Temperature Sensor
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