phase-error-e2x-b1 on an IVT Greenline HE: The compressor stops when the phase guard trips because of the lack of a phase or the presence of a phase sequence error. A voltage difference > 15 % between the phases also results in an alarm
Short answer
On an IVT heat pump, phase-error-e2x-b1 means: The compressor stops when the phase guard trips because of the lack of a phase or the presence of a phase sequence error. A voltage difference > 15 % between the phases also results in an alarm. 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: The compressor stops when the phase guard trips because of the lack of a phase or the presence of a phase sequence error. A voltage difference > 15 % between the phases also results in an alarm.
Part involved: E2x.B1.
When it shows: The compressor stops when the phase guard trips because of the lack of a phase or the presence of a phase sequence error. A voltage difference > 15 % between the phases also results in an alarm.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Acknowledge on control panel.
What you can check
- Note the full alarm text including the component designation (e.g. E21.T6) - IVT asks for it when you contact the dealer. Check the heat pump's breaker/isolator at the consumer unit is on and has not tripped. Contact the dealer if the alarm remains after acknowledgement. Acknowledge once on the control panel; if the alarm returns, contact the installer.
What the engineer will check
- Check supply phases, voltage balance (<15%), fuses, soft starter alarms and motor cut-out setting; reset motor cut-out.
Who to ask for: heat pump engineer.
Certification: Qualified electrician / heat pump engineer (electrical fault-finding).
What you might notice
Sources
- Installer Guide Greenline HE C6-C11 E6-E17 (6 720 643 409 (2010/03)) ↗ · 6 720 643 409 (2010/03) · page 6 720 643 409 p.83; 6 720 643 415 p.27 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026