P4 on an Immergas MAGIS M monobloc R32 - sold in UK as Alpha Magis M: Compressor discharge ('flow') temperature too high protection
Short answer
On an Immergas heat pump, P4 means: Compressor discharge ('flow') temperature too high protection. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Compressor discharge ('flow') temperature too high protection.
Likely causes:
- Same causes as P1.
- Lack of refrigerant.
- Tw_out / T1 / T5 sensor loose.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Manual reset: Manual 13.4: reset the safety device by switching the unit off and back on; if this fails contact your local dealer.
What you can check
- Check the outdoor unit is not blocked by leaves, debris or snow and has clear airflow.
- Note the code on the control panel and contact the installer / Alpha-Immergas authorised service.
- The manual says to reset the safety device by switching the unit off and back on; if the reset fails, contact the dealer - do not keep resetting.
What the engineer will check
- Same causes as P1.
- Lack of refrigerant.
- Tw_out / T1 / T5 sensor loose.
- Refrigerant-circuit diagnosis/charging (F-gas certified engineer).
Who to ask for: heat pump / refrigeration engineer.
Certification: F-gas certification for refrigerant circuit work (unit is hermetically sealed; installation needs no F-gas per Alpha).
What you might notice
Sources
- MAGIS M4-30 Block heat pumps - Use and Installation - Instructions and warnings (IE edition), *1.046978ENG* ↗ · 1.046978ENG · page 127 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026