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Heat pumps · Error codes · iDM Energiesysteme
043iDM Energiesysteme · TERRA SW (2013)

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
SeveritySafety 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

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026