998 on a NIBE heat pump: Starts: Display/machine has restarted [other NIBE documents: Display/installation has restarted]

What it means

The manual says: Starts: Display/machine has restarted [other NIBE documents: Display/installation has restarted].

Part involved: display / control unit.

When it shows: Display/machine has restarted; Display/installation has restarted.

Likely causes:

• Disruption in supply voltage.

Is it safe?

The heat pump keeps running.

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. No action needed unless it happens repeatedly; check for power cuts or tripping breakers.

What the engineer will check

• Check for supply interruptions or intermittent connections if restarts are frequent. NIBE lists: Disruption in supply voltage.

Who to ask for: NIBE-trained heat pump installer (NIBE PRO / VIP).

Certification: None specific beyond competent heat pump installer; electrical work to BS 7671.

What you might notice

• Intermittent fault

Sources

• TECHNICAL INFORMATION - ALARM LIST SMO 40 (TIF EN 2042-1, M12658EN) ↗ · TIF EN 2042-1 M12658EN · page 21 · Reviewed 23 September 2026

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026