J3-47 on a Daikin heat pump: Compressor shell thermistor abnormality
Short answer
On a Daikin heat pump, J3-47 means: Compressor shell thermistor abnormality. 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 Altherma 3 H HT (R-32 high temperature split)
The manual says: Compressor shell thermistor abnormality.
Part involved: thermistor / pressure sensor.
When it shows: Compressor is NOT running and compressor shell thermistor >165°C. Compressor is running for more than 20 minutes and compressor shell thermistor <−20°C.
Likely causes:
- Faulty compressor shell thermistor or connector fault.; Faulty main PCB.
On the Altherma 4 H (R-290)
The manual says: Discharge pipe Thermistor Abnormality.
Part involved: thermistor / pressure sensor.
When it shows: Discharge pipe Thermistor Abnormality.
Is it safe?
On the Altherma 3 H HT (R-32 high temperature split)
| 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: Manual reset via user interface.
On the Altherma 4 H (R-290)
| 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: Manual.
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.
- 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
On the Altherma 3 H HT (R-32 high temperature split)
- Perform a check of the compressor shell thermistor. ; Perform a check of the main PCB.
Who to ask for: Heat pump engineer (Daikin-trained).
Certification: Electrical competence to BS 7671 for sensor/PCB wiring; F-gas if a refrigerant-side sensor must be replaced.
On the Altherma 4 H (R-290)
- See Daikin service manual for this generation (not public).
Who to ask for: Heat pump engineer (Daikin-trained).
Certification: Electrical competence to BS 7671 for sensor/PCB wiring; F-gas if a refrigerant-side sensor must be replaced.
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- No heating on the Altherma 3 H HT (R-32 high temperature split): 1 report
Sources
- Service manual Daikin Altherma 3 H HT ECH2O EPRA14-18D + ETSH/ETSX(B)16P30/50E (ESIE22-11A) ↗ · ESIE22-11A · page 65 · Reviewed 23 September 2026
- Installer reference guide Daikin Altherma 4 H W EPSK/EPSKS + EPBX(U) (4P773390-1C) ↗ · 4P773390-1C · page 213 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026