E291 on a Samsung heat pump: High Pressure Sensor Error (open/short)
Short answer
On a Samsung heat pump, E291 means: High Pressure Sensor Error (open/short). 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: High Pressure Sensor Error (open/short).
Part involved: Refrigerant pressure sensor.
When it shows: Unit self-diagnosis: High Pressure Sensor Error (open/short).
Likely causes:
- Refrigerant pressure sensor open/short circuit or refrigerant leakage.
- Engineer checks per Samsung service manual: Check high pressure sensor connection/output; check for refrigerant leakage.
On the EHS TDM Plus (R410A)
The manual says: Refrigerant leakage or error on high pressure sensor (Short or Open).
Part involved: Refrigerant pressure sensor.
When it shows: Unit self-diagnosis: Refrigerant leakage or error on high pressure sensor (Short or Open).
Likely causes:
- Refrigerant pressure sensor open/short circuit or refrigerant leakage.
- Engineer checks per Samsung service manual: Check high pressure sensor connection/output; check for refrigerant leakage.
Is it safe?
On the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
On the EHS TDM Plus (R410A)
Switch the heat pump off at its isolator and call an engineer.
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
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; 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 high pressure sensor connection/output; check for refrigerant leakage. 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 TDM Plus (R410A)
- Check high pressure sensor connection/output; check for refrigerant leakage. 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
Sources
- EHS R290 Mono Outdoor Unit Installation Manual AE***CXYD** (EU) DB68-12496A-03 ↗ · DB68-12496A-03 · page p.24 · Reviewed 23 September 2026
- Samsung EHS TDM Plus Service Manual Code AC-07002A_0 (Feb 2017) ↗ · AC-07002A_0 · page p.66 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026