Heat pumps · Error codes · Daikin
HJ-11Daikin · Altherma
HJ-11 on a Daikin Altherma: Boiler abnormality detection Check boiler Refer to boiler manual
Short answer
On a Daikin heat pump, HJ-11 means: Boiler abnormality detection Check boiler Refer to boiler manual. 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: Boiler abnormality detection Check boiler Refer to boiler manual.
Part involved: water pressure sensor.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
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.
- Check the heating-system water pressure reading on the gauge/display: Daikin operation manuals ask users to check it is above 1 bar. If it is below that, report it to your installer (do not open the unit).
- 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.
What the engineer will check
- See Daikin service manual for this generation (not public).
Who to ask for: Heat pump installer / heating engineer.
Certification: None specific for water-side checks; MCS-certified installer recommended.
What you might notice
What owners and engineers report
11 owner and engineer reports mention this.
- No heating on the Altherma: 7 reports
- Keeps stopping / cutting out on the Altherma: 2 reports
- No hot water on the Altherma: 2 reports
Sources
- Installer reference guide Daikin Altherma H Hybrid EJHA04AAV3 + EHY2KOMB-A (4P531180-1E) ↗ · 4P531180-1E · page 219 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026