166 on a NIBE heat pump: Electrical anode incorrect: Fault in the electrical anode [other NIBE documents: Electrical anode fault]
Short answer
On a NIBE heat pump, 166 means: Electrical anode incorrect: Fault in the electrical anode [other NIBE documents: Electrical anode fault]. 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:
- Electrical anode incorrect: Fault in the electrical anode [other NIBE documents: Electrical anode fault].
- Low pressure alarm: F1145: low pressure sensor below limit; others: low pressure switch triggered.
Part involved: temperature limiter / anode; pressure switches/sensors, expansion valve.
When it shows: Fault in the electrical anode; Electrical anode fault F1145: low pressure sensor below limit; others: low pressure switch triggered.
Likely causes:
- Check electrical anode, its circuit board and cables.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Information only |
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.
- 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. Air source systems: check the outdoor unit is clear of leaves/snow/ice. Read the heating system pressure gauge and note the reading for your installer.
What the engineer will check
- Check temperature limiter (reset button inside unit), immersion heater and electrical anode circuit. NIBE lists: Check electrical anode, its circuit board and cables.
- Check heating medium flow, particle filter and circulation pump; check pressure switches/sensors, expansion valve, service valves and refrigerant charge (F-gas qualified).
Who to ask for: NIBE-trained heat pump installer (NIBE PRO / VIP); Heat pump engineer with F-gas qualification (NIBE-trained / NIBE PRO installer).
Certification: None specific beyond competent heat pump installer; electrical work to BS 7671; F-gas certification for refrigerant circuit work (plus flammable-refrigerant competence for R290/R32 models).
What you might notice
Sources
- ALARM LIST - NIBE products with Emmy display, Version 1747-1 (updated 2017-11-23) ↗ · 1747-1 · page 5 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026