Heat pumps · Error codes · Daikin
PJDaikin · Altherma HT (high temperature split)
PJ on a Daikin Altherma HT: Faulty combination of PCB
Short answer
On a Daikin heat pump, PJ means: Faulty combination of PCB. 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: Faulty combination of PCB.
Part involved: inter-unit communication / PCB combination.
When it shows: Make judgment according to communication data on whether or not the type of the inverter PCB is correct.
Likely causes:
- Mismatching of type of PCB.
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 shown on the user interface and note it, with the date/time, for your installer.
What the engineer will check
- Follow the service-manual troubleshooting flow chart for this code: check mismatching of type of PCB.
Who to ask for: Heat pump installer (Daikin-trained).
Certification: None specific; MCS-certified installer recommended.
What you might notice
Sources
- Service Manual Daikin ALTHERMA HT ERSQ/ERRQ 011-016 AA V1/Y1 + EKHBRD (ESIE09-08C) ↗ · ESIE09-08C · page 207 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026