E056 on a CTC control system alarm/information platform: Comm. error motor protection: HP control board (A5) cannot communicate with the motor protection (A4) (EcoLogic, EcoPart i600M, GS/GSi 600, i360, i555 numbering)
Short answer
On a CTC heat pump, E056 means: Comm. error motor protection: HP control board (A5) cannot communicate with the motor protection (A4) (EcoLogic, EcoPart i600M, GS/GSi 600, i360, i555 numbering). The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Comm. error motor protection: HP control board (A5) cannot communicate with the motor protection (A4) (EcoLogic, EcoPart i600M, GS/GSi 600, i360, i555 numbering).
Part involved: motor protection A4.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Manual reset: Press "Reset alarm" on the display; a persisting fault must be rectified before it can be reset.
What you can check
- Note the alarm code/text, the product model and serial number and contact your installer.
- Check the heat pump isolator/consumer-unit breakers are on.
What the engineer will check
- Check communication cables and connectors between the named boards.
- Check power supply to the named board.
Who to ask for: heat pump controls / electrical.
Certification: Electrical competence for work inside control panels.
What you might notice
Sources
- CTC EcoLogic XL/L/M II Installation and Maintenance Manual ↗ · 162 905 74-1 P93787 2026-02-06 · page 105 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026