Heat pumps · Error codes · Daikin
U8-01Daikin · Altherma
U8-01 on a Daikin Altherma: Connection with LAN adapter lost
Short answer
On a Daikin heat pump, U8-01 means: Connection with LAN adapter lost. The heat pump stops until the fault clears or is reset.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Connection with LAN adapter lost.
Part involved: LAN/WLAN adapter / cloud connection.
When it shows: Communication abnormality between indoor unit and router.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
The heat pump stops until the fault clears or is reset.
Resetting itself: yes.
Manual reset: Automatic.
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 your home router/Wi-Fi is switched on and working and has not been replaced or moved (router changes break the adapter/app link).
- Daikin documents this code as resetting automatically once the condition clears; if it keeps coming back, contact your installer.
- 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: Installer or homeowner with Daikin app/LAN adapter instructions.
Certification: None.
What you might notice
What owners and engineers report
7 owner and engineer reports mention this.
- App / connectivity problem on the Altherma: 7 reports
Sources
- Installer reference guide Daikin Altherma 3 R W ERGA04-08E + EHBH/EHBX-E (4P629085-1E) ↗ · 4P629085-1E · page 259 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026