E7 on a Mitsubishi Electric heat pump: Indoor (FTC)/outdoor communication failure - transmission error (FTC sends '0' but receives '1' 30 consecutive times)
Short answer
On a Mitsubishi Electric heat pump, E7 means: Indoor (FTC)/outdoor communication failure - transmission error (FTC sends '0' but receives '1' 30 consecutive times). 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 Ecodan
The manual says: Indoor (FTC)/outdoor communication failure - transmission error (FTC sends '0' but receives '1' 30 consecutive times).
Part involved: FTC board / connecting wire.
When it shows: Indoor (FTC)/outdoor communication failure - transmission error (FTC sends '0' but receives '1' 30 consecutive times).
Likely causes:
- 1 FTC transmission/receiving board fault; 2 Electrical noise on power supply; 3 Electrical noise on FTC-outdoor cable.
On the Ecodan Co2 Quhz
The manual says: Indoor/outdoor communication failure - transmission error.
Part involved: Thermal store FTC board.
When it shows: FTC sends '0' but receives '1' 30 consecutive times.
Likely causes:
- FTC transmission board fault; electrical noise on power supply or FTC-outdoor cable.
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 Co2 Quhz
| 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.
Manual reset: Press F4 (Reset) then F3 (Yes) on the main remote controller, or switch system off (installation manual).
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. A power cycle is a Mitsubishi first step for communication codes: switching the heat pump off and on at its isolator (outdoor and indoor supplies) once is acceptable.
What the engineer will check
On the Ecodan
- 1-3 Power indoor and outdoor off/on; if E7 persists replace FTC board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan Co2 Quhz
- Power off/on; replace FTC board if E7 persists.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
What you might notice
What owners and engineers report
37 owner and engineer reports mention this.
- Controller / thermostat problem on the Ecodan: 14 reports
- No heating on the Ecodan: 9 reports
- No hot water on the Ecodan: 9 reports
- Controller display blank on the Ecodan: 5 reports
Sources
- Ecodan EHPT20X-MEHEW Service Manual (OCH814A) ↗ · OCH814A · page 64 (10-4 Self-diagnosis and action) · Reviewed 23 September 2026
- Ecodan EHPT20Q VM2EA Service Manual (GCH15010C) ↗ · GCH15010C · page 40 (10-4 Self diagnosis and action) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026