Heat pumps · Error codes · Danfoss
04Danfoss · DHP-AT
04 on a Danfoss DHP-AT: Phase sequence error (only applies to 3-phase models)
Short answer
On a Danfoss heat pump, 04 means: Phase sequence error (only applies to 3-phase models). 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 sequence error (only applies to 3-phase models).
Part involved: Phase sequence error (only applies to 3-phase models).
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Note the 2-digit code. Check the heat pump's breaker/isolator at the consumer unit is on and has not tripped. If the code persists, call an engineer.
What the engineer will check
- Swap two incoming phases (3-phase models only).
Who to ask for: heat pump engineer.
What you might notice
Sources
- Installation Guide DHP-AT - Installation and service manual (VMGFI302 / AN089486453198) ↗ · VMGFI302 · page p.32 (section 10.1.1); safety functions pp.16-17 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026