115 on a NIBE heat pump: Sensor fault BT15: Sensor temporarily missing (information alarm)
Short answer
On a NIBE heat pump, 115 means: Sensor fault BT15: Sensor temporarily missing (information alarm). The manual does not say whether the heat pump stops.
Reviewed 23 September 2026 · 1 source
What it means
The manuals for this range word it in different ways:
- Sensor fault BT15: Sensor temporarily missing (information alarm).
- Sensor fault AZ30-BT22 supply air sensor: Heat pump has no connection with supply air sensor in ERS (AZ30).
Part involved: temperature/pressure sensor.
When it shows: Sensor temporarily missing (information alarm) Heat pump has no connection with supply air sensor in ERS (AZ30).
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Warning |
The manual does not say whether the heat pump stops.
Resetting itself: yes - information messages reset automatically when the cause is rectified.
Manual reset: Reset from the controller alarm menu ('reset alarm' / 'Reset alarm and try again'); alarm recurs if the cause remains.
What you can check
- Read the alarm text and the 'info/action' help on the controller display (VVM/SMO or S-series smartguide). NIBE's manuals let the homeowner select 'reset alarm' ('Reset alarm and try again' on S-series); if the lamp returns to normal the alarm has cleared. If it comes back, do not keep resetting: select 'aid mode' ('Auxiliary operation' on S-series) if offered, so any electric additional heat keeps heat/hot water going, and contact your installer.
What the engineer will check
- Check sensor and its connections/wiring against the wiring diagram; measure sensor resistance against the NIBE temperature/resistance table; check the relevant PCB input.
Who to ask for: NIBE-trained heat pump installer (NIBE PRO / VIP).
Certification: Electrical work to BS 7671 by a competent person.
What you might notice
Sources
- ALARM LIST - NIBE products with Emmy display, Version 1747-1 (updated 2017-11-23) ↗ · 1747-1 · page 4 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026