Heat pumps · Error codes · Ariston
2P2Ariston · NIMBUS NET R32 control platform (shared error list)
2P2 on an Ariston NIMBUS NET R32 control platform: Thermal cleanse not complete - sanitisation temperature not reached in 6 h
Short answer
On an Ariston heat pump, 2P2 means: Thermal cleanse not complete - sanitisation temperature not reached in 6 h. The heat pump keeps running. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Thermal cleanse not complete - sanitisation temperature not reached in 6 h.
Part involved: anti-legionella cycle / immersion heater.
Likely causes:
- Hot water drawn during the thermal sanitisation cycle.
- Heating element not activating.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running.
What you can check
- Avoid drawing large volumes of hot water during the thermal cleanse / boost cycle and see if the message clears.
- Note the error code shown on the Sensys HD interface and contact the installer / Ariston service.
What the engineer will check
- Check DHW drawing during sanitisation cycle.
- Check activation of the heating element.
Who to ask for: heat pump controls / hydronics.
Certification: Competent heating engineer; electrical competence for wiring checks.
What you might notice
Sources
- NIMBUS PLUS M NET R32 - Technical instructions for installation and maintenance (UK) - codes 3301719 3301720, doc 420000656201 EN ↗ · 420011311701 - 03/2024 · page 71 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026