Heat pumps · Error codes · Fujitsu
G12Fujitsu · AIRSTAGE Monobloc Comfort (R32)
G12 on a Fujitsu AIRSTAGE Monobloc Comfort: Water pressure too high
Short answer
On a Fujitsu heat pump, G12 means: Water pressure too high. 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: Water pressure too high.
Part involved: Water pressure too high.
Likely causes:
- Too much water in the circuit.
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.
Manual reset: unknown.
What you can check
- Note the error number shown after pressing the user interface. Check the heat pump breakers/isolators are on. Check the pressure gauge; do not drain the system yourself - contact the installer.
What the engineer will check
- Drain water slightly from the circuit.
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
- INSTALLATION - General Monobloc Comfort Duo, Monobloc 2 services air/water heat pump ↗ · U0780597_2690_EN_3 · page p.36 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026