HVACopediaViessmann · Boiler
F.12 Solar collector sensor short circuit
What the control is telling you
No solar DHW heating; short circuit on the collector temperature sensor. (Manual text for the measures of this code is partly duplicated from the outside sensor entry.)
Applies to: Vitodens 200-W B2HE 85, 120, 150, 199
Likely causes
- Shorted collector sensor or wiring
Test and repair steps
- Check the collector sensor and its wiring.
- Measure sensor input on the electronics module: about 3.3 V DC with sensor unplugged.
- Replace the faulty part.
Models that show this code
4 models in Vitodens 200-W B2HE
Other codes on the same units
- Connection error Display link lost to HMU
- F.100 PlusBus voltage error
- F.104 External fault message input active
- F.11 Solar collector sensor open circuit
- F.13 Outside temperature sensor open circuit
- F.14 Outside temperature sensor short circuit
- F.142 CAN bus communication error
- F.143 Fan overheating (air mass flow sensor / recirculation)
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Source: Viessmann Vitodens 200-W B2HE 85/120/150/199 Service Instructions 6167 813-24 (09/2026), Fault messages, p.62-73. Summarized in our own words; check the original manual for your model.
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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.