E9-03 on a Daikin Altherma 4 H: Malfunction of electronic expansion valve
Short answer
On a Daikin heat pump, E9-03 means: Malfunction of electronic expansion valve. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Malfunction of electronic expansion valve.
Part involved: refrigerant circuit / pressure protection.
When it shows: Electronic expansion valve is defective or not well connected.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: Power cycle.
What you can check
- Read the full error code and sub-code shown on the user interface (Malfunctioning screen; press the help button for Daikin's long description) and note it, with the date/time, for your installer.
- Look at the outdoor unit from outside: check the air inlet/outlet and fan grille are not blocked by leaves, debris, snow or heavy ice build-up (do not remove panels or touch the fan).
- Do NOT bleed radiators while an error/malfunction symbol is displayed: Daikin operation manuals warn refrigerant may have leaked into the water circuit - ventilate and call your installer.
- If heating/hot water has stopped, the operation manual lets the user confirm on the Malfunctioning screen whether the backup/booster heater may take over as emergency heating (much higher running cost) until the installer attends.
What the engineer will check
- See Daikin service manual for this generation (not public).
Who to ask for: F-gas certified heat pump engineer (Daikin-trained installer / Stand By Me partner).
Certification: UK F-gas certification (Category I) for refrigerant circuit work; R-290 (Altherma 4) also needs flammable-refrigerant/hydrocarbon competence.
What you might notice
Sources
- Installer reference guide Daikin Altherma 4 H W EPSK/EPSKS + EPBX(U) (4P773390-1C) ↗ · 4P773390-1C · page 211 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026