E407 on a Samsung heat pump: COMP down due to High Pressure Sensor Protection Control
Short answer
On a Samsung heat pump, E407 means: COMP down due to High Pressure Sensor Protection Control. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)
The manual says: COMP down due to High Pressure Sensor Protection Control.
Part involved: Compressor / refrigerant cycle protection.
When it shows: Unit self-diagnosis: COMP down due to High Pressure Sensor Protection Control.
Likely causes:
- Compressor stopped by refrigerant-cycle protection (pressure, discharge temperature, overload or compression ratio): e.g. refrigerant under/overcharge, blockage, poor water flow or airflow, sensor fault.
- Engineer checks per Samsung service manual: Check refrigerant pipe line blockage, high pressure sensor, refrigerant amount; in heating check water flow through the heat exchanger.
On the EHS Mono R32 (AE***RXYD*G)
The manual says: Comp down due to high pressure.
Part involved: Compressor / refrigerant cycle protection.
When it shows: Unit self-diagnosis: Comp down due to high pressure.
Likely causes:
- Compressor stopped by refrigerant-cycle protection (pressure, discharge temperature, overload or compression ratio): e.g. refrigerant under/overcharge, blockage, poor water flow or airflow, sensor fault.
- Engineer checks per Samsung service manual: Check refrigerant pipe line blockage, high pressure sensor, refrigerant amount; in heating check water flow through the heat exchanger.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: yes - Samsung SM lists product operation as "restart operation".
Manual reset: unknown.
What you can check
- Note the full error code shown on the controller; check the heat pump breaker/isolator in the consumer unit is ON; check the outdoor unit is not blocked by leaves, debris or snow and air can flow freely; check the heating system pressure gauge reading (typically 1-2 bar when cold; do not top up unless you have been shown how); then contact your installer or Samsung service; Samsung manuals do not describe a homeowner reset for this code.
What the engineer will check
On the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)
- Check refrigerant pipe line blockage, high pressure sensor, refrigerant amount; in heating check water flow through the heat exchanger. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: F-gas certified refrigeration/heat pump engineer; R290 (A3 flammable refrigerant) competence.
Certification: F-gas certification (UK F-gas Regulation; e.g. City & Guilds 2079 Cat I); R290/flammable refrigerant handling training (e.g. hydrocarbon refrigerant course).
On the EHS Mono R32 (AE***RXYD*G)
- Check refrigerant pipe line blockage, high pressure sensor, refrigerant amount; in heating check water flow through the heat exchanger. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: F-gas certified refrigeration/heat pump engineer.
Certification: F-gas certification (UK F-gas Regulation; e.g. City & Guilds 2079 Cat I).
What you might notice
What owners and engineers report
9 owner and engineer reports mention this.
- No heating on the EHS Mono R32 (AE***RXYD*G): 6 reports
- Keeps stopping / cutting out on the EHS Mono R32 (AE***RXYD*G): 2 reports
- Intermittent fault on the EHS Mono R32 (AE***RXYD*G): 1 report
Sources
- EHS R290 Mono Outdoor Unit Installation Manual AE***CXYD** (EU) DB68-12496A-03 ↗ · DB68-12496A-03 · page p.24 · Reviewed 23 September 2026
- EHS R-32 Mono Outdoor Unit Installation Manual (EU) DB68-08408A-07 ↗ · DB68-08408A-07 · page p.43 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026