E438 on a Samsung heat pump: EVI EEV Opening Error
Short answer
On a Samsung heat pump, E438 means: EVI EEV Opening Error. 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: EVI EEV Opening Error.
Part involved: Electronic expansion valve (EEV).
When it shows: Unit self-diagnosis: EVI EEV Opening Error.
Likely causes:
- Electronic expansion valve (EEV) fault: coil, connector, valve body or leakage.
- Engineer checks per Samsung service manual: Check EVI EEV (leakage), intercooler, and EVI EEV connector insertion.
On the EHS TDM Plus (R410A)
The manual says: EVI (ESC) EEV leakage or internal leakage of intercooler or incorrect connector insertion of EVI (ESC) EEV.
Part involved: Electronic expansion valve (EEV).
When it shows: Unit self-diagnosis: EVI (ESC) EEV leakage or internal leakage of intercooler or incorrect connector insertion of EVI (ESC) EEV.
Likely causes:
- Electronic expansion valve (EEV) fault: coil, connector, valve body or leakage.
- Engineer checks per Samsung service manual: Check EVI EEV (leakage), intercooler, and EVI EEV connector insertion.
Is it safe?
| 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 EVI EEV (leakage), intercooler, and EVI EEV connector insertion. 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); R290/flammable refrigerant handling training (e.g. hydrocarbon refrigerant course).
On the EHS TDM Plus (R410A)
- Check EVI EEV (leakage), intercooler, and EVI EEV connector insertion. 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).
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- Insufficient heating (house not warm enough) on the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K): 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
- 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