EE on a Mitsubishi Electric heat pump: Combination error between FTC and outdoor unit
Short answer
On a Mitsubishi Electric heat pump, EE means: Combination error between FTC and outdoor unit. 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 · 6 sources
What it means
On the Ecodan
The manual says: Combination error between FTC and outdoor unit.
Part involved: FTC / outdoor unit combination.
When it shows: FTC detects incompatible outdoor unit (FTC6/FTC7 service manuals: R410A outdoor unit combined incorrectly).
Likely causes:
- Incompatible FTC/outdoor unit combination.
On the Ecodan Puhz Sw Split
The manual says: Incorrect connection: the outdoor unit does not receive the signals of an interface (I/F) or flow temperature controller (FTC).
Part involved: FTC / interface unit connection.
When it shows: Outdoor unit does not receive I/F or FTC signals.
Likely causes:
- 1 A device other than an interface unit or flow temperature controller is connected to the outdoor unit.
On the Ecodan R290 Puz Wz
The manual says: Incorrect connection: the outdoor unit does not receive the signals of an interface (I/F) or flow temperature controller (FTC).
Part involved: FTC / interface unit connection.
When it shows: Outdoor unit does not receive I/F or FTC signals.
Likely causes:
- 1 A device other than an interface unit or flow temperature controller is connected to the outdoor unit.
On the Ecodan R32 Puz Wm
The manual says: Incorrect connection: the outdoor unit does not receive the signals of an interface (I/F) or flow temperature controller (FTC).
Part involved: FTC / interface unit connection.
When it shows: Outdoor unit does not receive I/F or FTC signals.
Likely causes:
- 1 A device other than an interface unit or flow temperature controller is connected to the outdoor unit.
On the Ecodan R32 Zubadan Puz Hwm
The manual says: Incorrect connection: the outdoor unit does not receive the signals of an interface (I/F) or flow temperature controller (FTC).
Part involved: FTC / interface unit connection.
When it shows: Outdoor unit does not receive I/F or FTC signals.
Likely causes:
- 1 A device other than an interface unit or flow temperature controller is connected to the outdoor unit.
On the Ecodan Ultra Quiet Puhz W Vaa
The manual says: Incorrect connection: the outdoor unit does not receive the signals of an interface (I/F) or flow temperature controller (FTC).
Part involved: FTC / interface unit connection.
When it shows: Outdoor unit does not receive I/F or FTC signals.
Likely causes:
- 1 A device other than an interface unit or flow temperature controller is connected to the outdoor unit.
Is it safe?
On the Ecodan
| 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-resetting; code remains until reset.
Manual reset: Installation manuals: press F4 (RESET) then F3 (Yes) on the main remote controller (older controllers: hold button E for 3 s); 'To cancel error codes please switch system off'. Fix the cause first.
On the Ecodan Puhz Sw 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: 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.
On the Ecodan R290 Puz Wz
| 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.
On the Ecodan R32 Puz Wm
| 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.
On the Ecodan R32 Zubadan Puz Hwm
| 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.
On the Ecodan Ultra Quiet Puhz W Vaa
| 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 (Mitsubishi user manuals: 'Make a note of the error code number and contact installer'). Check the heat pump breaker/isolator at the consumer unit is on and read the primary system pressure gauge (if fitted) so you can report it. A single reset from the main remote controller (RESET, then Yes) may be tried; if the code returns, do not keep resetting. Do not open the outdoor unit, cylinder/hydrobox or any casing.
What the engineer will check
On the Ecodan
- Check combination of FTC and outdoor unit.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan Puhz Sw Split
- 1 Connect an I/F or FTC to the unit (check FTC/outdoor combination).
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan R290 Puz Wz
- 1 Connect an I/F or FTC to the unit (check FTC/outdoor combination).
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan R32 Puz Wm
- 1 Connect an I/F or FTC to the unit (check FTC/outdoor combination).
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan R32 Zubadan Puz Hwm
- 1 Connect an I/F or FTC to the unit (check FTC/outdoor combination).
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan Ultra Quiet Puhz W Vaa
- 1 Connect an I/F or FTC to the unit (check FTC/outdoor combination).
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
What you might notice
What owners and engineers report
20 owner and engineer reports mention this.
- No heating on the Ecodan: 9 reports
- No hot water on the Ecodan: 9 reports
- Heat pump will not start on the Ecodan: 2 reports
Sources
- Ecodan EHPT20X-MEHEW Service Manual (OCH814A) ↗ · OCH814A · page 64 (10-4 Self-diagnosis and action) · Reviewed 23 September 2026
- Ecodan PUHZ-SW(75-100-120)(V-Y)HA-BS Service Manual (OCH755) ↗ · OCH755 · page OCH755 p.23; OCH525C p.21 · Reviewed 23 September 2026
- PUZ-WZ(85-100-120)(V-Y)AA(-BS) Service_Manual (OCH880) ↗ · OCH880 · page OCH880 p.37; OCH816 p.33 · Reviewed 23 September 2026
- Ecodan PUZ-WM(50-60-85-112)V(H-A)A Service Manual (OCH727A) ↗ · OCH727A · page 24 · Reviewed 23 September 2026
- Ecodan PUZ-HWM140(V-Y)HA Service Manual (OCH748A) ↗ · OCH748A · page 21 · Reviewed 23 September 2026
- PUHZ-W85-112VAA(-BS) Service Manual (OCH681) ↗ · OCH681 · page 15 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026