Heat pumps · Error codes · Atlantic
ODU3-4FAtlantic
ODU3-4F on an Atlantic heat pump: Heat-exchange thermistor (outlet) error
Short answer
On an Atlantic heat pump, ODU3-4F means: Heat-exchange thermistor (outlet) error. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
The manual says: Heat-exchange thermistor (outlet) error.
Likely causes:
- Temperature sensor short-circuit, open circuit, unplugged or faulty.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
What you can check
- Note the error number/LED pattern shown and give it to your installer.
What the engineer will check
- Check sensor wiring and connector.
- Measure sensor resistance; replace if faulty.
Who to ask for: heat pump / electrical.
Sources
- alféa excellia duo Maintenance Document (U0546279_1738_EN_16) ↗ · U0546279_1738_EN_16 · page 73 · Reviewed 23 September 2026
- alféa hybrid duo Installation and commissioning instructions (doc 1440-13) ↗ · 1440-13 · page 67 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026