P20 on a Toshiba heat pump: High pressure protection operation
Short answer
On a Toshiba heat pump, P20 means: High pressure protection operation. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 4 sources
What it means
On the R32 Estia 1-Series (split, Wall-Mounted and All-in-One)
The manual says: High pressure protection operation.
Part involved: refrigerant charge, PMV, valves, pressure switch/sensor.
When it shows: Stop by high-pressure release control or PD sensor reaches 4.19 MPa.
Likely causes:
- Service valve not fully open.
- PMV defect.
- Outdoor fan system/clogging.
- Refrigerant overcharge.
- PD sensor.
- Water piping too short - buffer tank or lower set temperature.
On the Estia (Series 4) Standard & Powerful
The manual says: High pressure protection operation.
Part involved: refrigerant charge, PMV, valves, pressure switch/sensor.
When it shows: High-pressure release stop; TL 63C in cooling or TWO 60C in heating/DHW.
Likely causes:
- Service valve not fully open.
- PMV defect.
- Outdoor fan/clogging.
- Refrigerant overcharge.
- TL/TWO sensors.
On the Estia 5 Series (Standard)
The manual says: High pressure protection operation.
Part involved: refrigerant charge, PMV, valves, pressure switch/sensor.
When it shows: High-pressure release stop; TL 63C in cooling or TWO 60C in heating/DHW.
Likely causes:
- Service valve not fully open.
- PMV defect.
- Outdoor fan/clogging.
- Refrigerant overcharge.
- TL/TWO sensors.
On the Estia 5 Series Powerful (Hi Power / Extreme)
The manual says: High pressure protection operation.
Part involved: refrigerant charge, PMV, valves, pressure switch/sensor.
When it shows: Trigger thresholds not printed in the IM; see SM.
Likely causes:
- Service valve not fully open.
- PMV defect.
- Outdoor fan/clogging.
- Refrigerant overcharge.
- PD sensor value.
- Water piping too short - buffer tank or lower set temperature.
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 outdoor unit is not blocked by leaves, debris, snow or ice, and that nothing is covering the air inlet/outlet.
What the engineer will check
On the R32 Estia 1-Series (split, Wall-Mounted and All-in-One)
- Follow manufacturer's check-code flowchart.
- Service valve not fully open.
- PMV defect.
- Outdoor fan system/clogging.
- Refrigerant overcharge.
- PD sensor.
- Water piping too short - buffer tank or lower set temperature.
Who to ask for: F-gas certified refrigeration / heat pump engineer.
Certification: F-gas Category I; R32 is A2L mildly flammable - trained handler required.
On the Estia (Series 4) Standard & Powerful
- Follow manufacturer's check-code flowchart.
- Service valve not fully open.
- PMV defect.
- Outdoor fan/clogging.
- Refrigerant overcharge.
- TL/TWO sensors.
Who to ask for: F-gas certified refrigeration / heat pump engineer.
Certification: F-gas Category I; R32 is A2L mildly flammable - trained handler required.
On the Estia 5 Series (Standard)
- Follow manufacturer's check-code flowchart.
- Service valve not fully open.
- PMV defect.
- Outdoor fan/clogging.
- Refrigerant overcharge.
- TL/TWO sensors.
Who to ask for: F-gas certified refrigeration / heat pump engineer.
Certification: F-gas Category I; R32 is A2L mildly flammable - trained handler required.
On the Estia 5 Series Powerful (Hi Power / Extreme)
- Follow manufacturer's check-code flowchart.
- Service valve not fully open.
- PMV defect.
- Outdoor fan/clogging.
- Refrigerant overcharge.
- PD sensor value.
- Water piping too short - buffer tank or lower set temperature.
Who to ask for: F-gas certified refrigeration / heat pump engineer.
Certification: F-gas Category I; R32 is A2L mildly flammable - trained handler required.
What you might notice
Sources
- Air to Water Heat Pump Service Manual - Wall Mounted Type (File No. AE0-2101W) ↗ · AE0-2101W · page p.118 (printed page; PDF page +1) · Reviewed 23 September 2026
- Quick Reference Air to Water Heat Pump Series 4 Standard & Powerful Types ↗ · Quick Reference Series 4 Standard & Powerful (undated) · page p.64 (printed page; PDF page +1) · Reviewed 23 September 2026
- Air to Water Heat Pump Service Manual (File No. A10-1704) - Estia 5 Series Indoor/Outdoor ↗ · A10-1704 · page p.92 (printed page; PDF page +1) · Reviewed 23 September 2026
- Hydro Unit Installation Manual EF99812301-4 (Powerful) ↗ · EF99812301-4 · page p.61 (printed page; PDF page +1) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026