043 on an iDM Energiesysteme TERRA SW: Hot gas temperature too low - lockout: The heat pump was switched off due to too low hot gas temperature (> 5 times in 24 h)
Short answer
On an iDM Energiesysteme heat pump, 043 means: Hot gas temperature too low - lockout: The heat pump was switched off due to too low hot gas temperature (> 5 times in 24 h). 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: Hot gas temperature too low - lockout: The heat pump was switched off due to too low hot gas temperature (> 5 times in 24 h).
Part involved: Hot gas temperature too low - lockout.
When it shows: The heat pump was switched off due to too low hot gas temperature (> 5 times in 24 h).
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Unlock/acknowledge via Navigator (max. once after 023); call service.
What you can check
- Note the fault number and text shown after tapping the fault symbol on the Navigator display. This is a locking (Verriegelung) fault - iDM says to call customer service; do not repeatedly unlock it (after fault 023 the unit may be unlocked at most once).
What the engineer will check
- Diagnose per iDM service documentation for the unit (not obtained): check the monitored circuit/component named in the fault.
Who to ask for: heat pump engineer.
Certification: F-Gas category I certificate (refrigerant circuit work).
What you might notice
Sources
- IDM Wärmepumpen mit Navigatorregelung 2.0 - Bedienungsanleitung (812152 Rev.3) ↗ · 812152 Rev.3 · page p.70 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026