UH on a Mitsubishi Electric heat pump: Current sensor error or input current error
Short answer
On a Mitsubishi Electric heat pump, UH means: Current sensor error or input current error. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 9 sources
What it means
On the Ecodan Hydrodan
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor -1.0 A to 1.0 A during operation, or input current 40 A / 37 A for 10 s.
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan Puhz Sw Split
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor -1.0 A to 1.0 A in operation (ignored in test run), or input current 40 A / 37 A for 10 s (V models).
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan Puhz W Monobloc
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor reads -1.0 A to 1.0 A during compressor operation (ignored in test run), or input current above limit.
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan R290 Puz Wz
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor -1.0 A to 1.0 A during operation, or input current over limit: WZ50-80V 40 A instant / 37 A for 10 s; WZ85V 38/34 A; WZ100/120V 40/37 A.
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan R32 Puz Wm
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor -1.0 A to 1.0 A during compressor operation (ignored in test run), or input current 40 A (instant) / 37 A for 10 s (V models).
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan R32 Zubadan Puz Hwm
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor -1.0 A to 1.0 A in operation, or input current 40 A / 39 A for 10 s (HWM140V only).
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan Ultra Quiet Puhz W Vaa
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor -1.0 A to 1.0 A during operation (ignored in test run), or input current 40 A / 37 A for 10 s (W85V, W112V).
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan Zubadan Puhz Hw Monobloc
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor -1.0 A to 1.0 A during operation, or input current 40 A / 37 A for 10 s (HW140V only).
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
On the Ecodan Zubadan Puhz Shw Split
The manual says: Current sensor error or input current error.
Part involved: Current sensor (outdoor power circuit board).
When it shows: Current sensor reads -1.0 A to 1.0 A during compressor operation (ignored in test run), or input current above limit.
Likely causes:
- 1 Disconnection of compressor wiring; 2 Defective current sensor circuit on outdoor power circuit board; 3 Decrease of power supply voltage; 4 Leakage or shortage of refrigerant.
Is it safe?
Switch the heat pump off at its isolator and call an engineer.
| 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: Not stated as auto-recovering in the service manual; code is logged in the outdoor unit error history.
Manual reset: Clear via RESET on the main remote controller after the cause is fixed; service manual actions include switching power off and on to recheck.
What you can check
- Note the code, unit and ref. address shown on the main remote controller and contact your installer. Do not reset repeatedly: this is an electrical/compressor protection code. If the breaker or RCD has tripped, or there is a burning smell, leave the heat pump switched off at its isolator and call an engineer. Do not open any casing.
What the engineer will check
On the Ecodan Hydrodan
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R32, A2L mildly flammable).
On the Ecodan Puhz Sw Split
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R410A).
On the Ecodan Puhz W Monobloc
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R410A).
On the Ecodan R290 Puz Wz
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification plus competence for flammable A3 refrigerant (R290).
On the Ecodan R32 Puz Wm
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R32, A2L mildly flammable).
On the Ecodan R32 Zubadan Puz Hwm
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R32, A2L mildly flammable).
On the Ecodan Ultra Quiet Puhz W Vaa
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R410A).
On the Ecodan Zubadan Puhz Hw Monobloc
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R410A).
On the Ecodan Zubadan Puhz Shw Split
- 1 Correct compressor wiring (U-V-W); 2 Replace outdoor power circuit board; 3 Check power supply; 4 Check refrigerant leakage.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (refrigeration / F-gas).
Certification: UK F-gas Category I certification (R410A).
What you might notice
Sources
- Ecodan Hydrodan EHWT17D-MHEDW Installation Manual RK79D203K04 ↗ · RK79D203K04 · page 51 (PDF p.52) · Reviewed 23 September 2026
- Ecodan PUHZ-SW(75-100-120)(V-Y)HA-BS Service Manual (OCH755) ↗ · OCH755 · page OCH755 p.27; OCH525C p.25 · Reviewed 23 September 2026
- Ecodan PUHZ-W112VHA-BS Service Manual (OCH562D) ↗ · OCH562D · page OCH562D p.22; OCH605A p.19; OCH465D p.24; OCH439N p.59 · Reviewed 23 September 2026
- PUZ-WZ(85-100-120)(V-Y)AA(-BS) Service_Manual (OCH880) ↗ · OCH880 · page OCH880 p.41; OCH816 p.37 · Reviewed 23 September 2026
- Ecodan PUZ-WM(50-60-85-112)V(H-A)A Service Manual (OCH727A) ↗ · OCH727A · page 28 · Reviewed 23 September 2026
- Ecodan PUZ-HWM140(V-Y)HA Service Manual (OCH748A) ↗ · OCH748A · page 25 · Reviewed 23 September 2026
- PUHZ-W85-112VAA(-BS) Service Manual (OCH681) ↗ · OCH681 · page 19 · Reviewed 23 September 2026
- Ecodan PUHZ-HW140VHA2-BS / PUHZ-HW140YHA2-BS Service Manual (OCH439N) ↗ · OCH439N · page 59 · Reviewed 23 September 2026
- PUHZ-SHW112-140V/YHA Service Manual (OCH526) ↗ · OCH526 · page 29 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026