552 on a Vaillant aroTHERM: Fault detected: Operating pressure
Short answer
On a Vaillant heat pump, 552 means: Fault detected: Operating pressure. The heat pump keeps running with some functions stopped.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Fault detected: Operating pressure.
Part involved: Fault detected: Operating pressure.
Likely causes:
- Status/fault state reported by the heat pump; see the corresponding F-code in the fault overview for causes.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
The heat pump keeps running with some functions stopped.
Resetting itself: status changes automatically; the associated F-code (if any) needs reset.
Manual reset: see associated F-code.
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). Check the outdoor unit's air inlet and outlet are not blocked by leaves, debris, snow or ice build-up and clear any loose debris from around it (do not open the casing, poke the fins or use tools). Do not keep resetting the unit; report the code to your installer (the operating instructions for this product were not checked for a homeowner reset procedure). If you smell gas/solvent near the outdoor unit or hear hissing, switch the heat pump off at the isolator, keep ignition sources away and call an engineer.
What the engineer will check
- Read status in Live Monitor and the fault list; diagnose via the matching F-code (e.g. 580 flow rate -> F.532, 581 -> F.753, 584 -> F.582, 585 -> F.037/F.754, 588 -> F.042, 589 -> F.086, 590 -> F.755).
Who to ask for: F-gas certified refrigeration engineer with heat pump experience (R290 flammable-refrigerant competence required for aroTHERM plus / GeniaAir).
Certification: F-gas Category I (Regulation (EU) 517/2014 as retained in GB) certificate; flammable (R290) refrigerant training for R290 units.
What you might notice
What owners and engineers report
2 owner and engineer reports mention this.
- No heating on the aroTHERM: 2 reports
Sources
- Installation instructions aroTHERM VWL 55/3 A 230 V, VWL 85/3 A 230 V (GB) ↗ · 0020217827_03 · page VWL ../3 A 0020217827_03 p.29; VWL ../2 A 0020147164_09 Appendix D (status codes) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026