A15 on a Toshiba R32 Estia 1-Series: Pump failure (for zone 2)
Short answer
On a Toshiba heat pump, A15 means: Pump failure (for zone 2). The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Pump failure (for zone 2).
Part involved: circulation pump, flow switch/sensor, strainer, water pipework.
When it shows: Zone 2 pump stopped.
Likely causes:
- Low supply voltage.
- Zone 2 pump locked by dirt.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: no.
Manual reset: Cause must be fixed by an engineer; hardware faults reappear until repaired.
What you can check
- Note the check code shown on the remote controller and the outdoor/hydro model numbers before contacting an engineer.
- Check the system pressure gauge on the hydro unit / heating system shows the normal fill pressure the installer set (the manuals ask for at least about 1 bar); if it is low, report it to the engineer. Check the filling loop is closed.
- Check radiator/underfloor zone valves and thermostats are calling for heat and have not all been turned off.
What the engineer will check
- Follow manufacturer's check-code flowchart.
- Low supply voltage.
- Zone 2 pump locked by dirt.
Who to ask for: Heat pump / heating engineer (hydronic).
Certification: Heat pump installer competence (e.g. MCS-installer staff); no F-gas needed unless refrigerant work follows.
What you might notice
Sources
- R32 Estia Hydro Unit (Wall Mounted) Installation Manual 2F30151001 rev 05 ↗ · 2F30151001-05 · page printed p.34 (PDF p.35) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026