9B on a Viessmann Vitotronic 200: Vitocal 300-G/333-G: Temperature of power factor correction filter too high
Short answer
On a Viessmann heat pump, 9B means: Vitocal 300-G/333-G: Temperature of power factor correction filter too high. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
The manuals for this range word it in different ways:
- Vitocal 300-G/333-G: Temperature of power factor correction filter too high.
- Temperature of power factor correction filter too high.
- Retn temp.sensor solar: No solar DHW heating or; No heating of the ice store.
Part involved: Vitocal 300-G/333-G: Temperature of power factor correction filter too high; Temperature of power factor correction filter too high; Retn temp.sensor solar.
When it shows: Type "Note" (H) - triggers "07 Refrigerant circuit" on the heat pump control unit. Heat pump characteristics: Compressor OFF No solar DHW heating or; No heating of the ice store.
Likely causes:
- Vitocal 300-G/333-G: Temperature of power factor correction filter too high.
- Temperature of power factor correction filter too high.
- With internal solar control function: Lead break, return temperature sensor With Vitosolic 200: Lead break, ice store temperature sensor.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Not stated in 6150133.
Manual reset: Refrigerant circuit messages cannot be acknowledged in the message history (6150133 p.155); acknowledge the resulting 05/07/A9 message on the control unit.
What you can check
- This code is only visible to engineers in the service menu (Diagnosis > Refrigerant circuit > Message history); homeowners see message 05, 07 or A9 - note that code and call your contractor.
- Note the 2-character message code and message text shown on the Vitotronic 200 display (press OK for details) and give them to your heating contractor (operating instructions 5817913 p.56).
- You may acknowledge the message once with OK as described in the Vitotronic 200 operating instructions; if it reappears, do not keep acknowledging it - call your contractor.
- Check the heat pump breaker/isolator in the consumer unit is ON (do not repeatedly reset a breaker or RCD that keeps tripping).
What the engineer will check
- Test coil resistance at compressor.
- Resistance on all windings should be similar (± 10 %). Use measuring device suitable for m Ω. Replace inverter if required.
- Resistance on all windings must be similar (±10 %). For mΩ use a suitable measuring device. Replace inverter if necessary.
- Resistance on all windings must be similar (10 %). For m use a suita- ± Ω ble measuring device. Replace inverter if required.
- Check resistance value (NTC 10 k Ω) at plug F23: See "Controller and sensor PCB". Replace sensor if required. Check ice store temperature sensor. Replace ….
Who to ask for: Viessmann-trained heat pump engineer with F-gas refrigeration certification; Viessmann-trained heat pump installer/service engineer.
Certification: F-gas certificate (UK F-gas Regulations; Viessmann: refrigerant work by authorised refrigeration engineers only).
What you might notice
Sources
- Service instructions Vitotronic 200 type WO1C heat pump control unit (air/water split & monobloc, brine/water) (6150133, 2023-07) ↗ · 6150133 VSA00004 · pages 177, 165, 185 · Reviewed 23 September 2026
- Service instructions Vitotronic 200 WO1C (5790974 GB, 2023-09) – brine/water & split variants ↗ · 5790974 VSA00002 · page 80 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026