Heat pumps · Error codes · IVT
check-connection-to-room-sensor-e1x-ttIVT · Greenline HE
check-connection-to-room-sensor-e1x-tt on an IVT Greenline HE: Activated when communication with the room sensor is terminated
Short answer
On an IVT heat pump, check-connection-to-room-sensor-e1x-tt means: Activated when communication with the room sensor is terminated. The heat pump keeps running. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Activated when communication with the room sensor is terminated.
Part involved: E1x.TT.
When it shows: Activated when communication with the room sensor is terminated.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running.
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. Acknowledge once on the control panel; if the alarm returns, contact the installer.
What the engineer will check
- Measure sensor and cable resistance against the IVT sensor table; check connections on the I/O board; replace sensor or cable. Check CAN-bus cable and connections between boards/room sensor; check board power.
Who to ask for: heat pump engineer.
What you might notice
Sources
- Installer Guide Greenline HE C6-C11 E6-E11 1x230V (6 720 802 419 (2012/06) en) ↗ · 6 720 802 419 (2012/06) · page 6 720 802 419 p.70 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026