55 on a Viessmann Vitotronic 200: Too little refrigerant
Short answer
On a Viessmann heat pump, 55 means: Too little refrigerant. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manuals for this range word it in different ways:
- Too little refrigerant.
- Too little refrigerant; Electronic expansion; valve for suction gas fully open.
- Refrigerant loss.
Part involved: Too little refrigerant; Too little refrigerant; Electronic expansion; valve for suction gas fully open; Refrigerant loss.
When it shows: Type "Note" (H) - triggers "07 Refrigerant circuit" on the heat pump control unit. Heat pump characteristics: Compressor OFF Type "Note" (H) - triggers "07 Refrigerant circuit" on the heat pump control unit. Heat pump characteristics: Compressor does not start.
Likely causes:
- Too little refrigerant.
- Too little refrigerant; Electronic expansion; valve for suction gas fully open.
- Refrigerant loss.
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.
What the engineer will check
- Check amount of refrigerant. Adjust the amount of refrigerant if necessary.
- Check amount of refrigerant. Adjust.
- if necessary. Check plug at connection J11: See.
- "EEV PCB [4] ". Check stepper motor of electronic.
- expansion valve.
- Check refrigerant charge.
- Check refrigerant circuit for leaks.
Who to ask for: Viessmann-trained heat pump engineer with F-gas refrigeration certification.
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 169, 175, 163, 184 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026