Heat pumps · Error codes · CTC
E052CTC · control system alarm/information platform (error-code grouping)
E052 on a CTC control system alarm/information platform: Phase 1 missing: phase failure detected
Short answer
On a CTC heat pump, E052 means: Phase 1 missing: phase failure detected. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Phase 1 missing: phase failure detected.
Part involved: mains supply L1.
Likely causes:
- Phase failure / mains interruption.
Is it safe?
| 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.
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 consumer-unit breakers/fuses for the heat pump are on (do not open the unit).
What the engineer will check
- Measure all three phases at the heat pump supply terminals.
- Check supply fuses and cabling.
Who to ask for: electrical.
Certification: Qualified electrician.
What you might notice
Sources
- CTC EcoZenith i255 Installation and Maintenance Manual (400V 3N~/230V 1N~/230V 3~) ↗ · 162 505 67-9 CR01164 2026-05-10 · page 80 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026