Heat pumps · Error codes · CTC
I023CTC · control system alarm/information platform (error-code grouping)
I023 on a CTC control system alarm/information platform: Ext. Ctrl Heating 3
Short answer
On a CTC heat pump, I023 means: Ext. Ctrl Heating 3. The heat pump keeps running.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Ext. Ctrl Heating 3.
Part involved: control system status.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Information only |
| Engineer needed? | No |
The heat pump keeps running.
Resetting itself: Message clears when the condition ends.
What you can check
- Read the message; it is informational.
- Check timer/tariff/holiday/remote-control settings on the controller if heating or hot water is unexpectedly off.
What the engineer will check
- Review installer settings (tariff, SmartGrid, remote control inputs, compressor block, power limitation).
Who to ask for: heat pump controls.
What you might notice
Sources
- CTC EcoLogic XL/L/M II Installation and Maintenance Manual ↗ · 162 905 74-1 P93787 2026-02-06 · page 103 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026