441 on a Fujitsu WATERSTAGE split: BX31 no function (2nd zone sensor not configured if 2nd circuit kit)
Short answer
On a Fujitsu heat pump, 441 means: BX31 no function (2nd zone sensor not configured if 2nd circuit kit). 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: BX31 no function (2nd zone sensor not configured if 2nd circuit kit).
Part involved: sensor/controller: BX31.
Likely causes:
- Short-circuit; unplugged or disconnected sensor; faulty sensor; other fault.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: no.
What you can check
- Note the error number shown after pressing the Info (i) key on the Waterstage user interface. Check the heat pump breakers/isolators are on. The user manual RESET key/'Reset HP' is for installers ('do not use during normal operation') - contact your installer if the fault remains.
What the engineer will check
- Check the sensor's wiring; set parameter 5700 to 2, 4 or 6 (1768-3).
Who to ask for: Heat pump / refrigeration engineer (manufacturer-trained).
Certification: F-gas certification for refrigerant-circuit work; electrical competence (Part P/18th Edition) for PCB/wiring.
What you might notice
Sources
- Maintenance Document - Air to Water Heat Pump Split single service and integrated DHW type (Super High Power) ↗ · 2105_EN_1 · page SHP SM p.5; 1768-3 p.68 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026