N.200 on a Glow-worm GeniaAir: Invalid signal for outdoor unit temperature sensor for the air inlet
Short answer
On a Glow-worm heat pump, N.200 means: Invalid signal for outdoor unit temperature sensor for the air inlet. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Invalid signal for outdoor unit temperature sensor for the air inlet.
Part involved: Invalid signal for outdoor unit temperature sensor for the air inlet.
Likely causes:
- Temperature sensor defective; interruption in the wiring harness.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: no - irreversible; requires action.
Manual reset: engineer rectifies the cause.
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). Glow-worm's MiPro Sense operating instructions say always contact your competent person in the event of a fault message; until they arrive you may select a limp-home (back-up heater) setting on the control, which is expensive to run.
What the engineer will check
- Check and, if required, replace the temperature sensor; check the wiring harness and plug connections.
Who to ask for: Vaillant-trained heat pump installer/engineer (MCS-certified installer).
Certification: MCS installer certification; Vaillant product training recommended.
What you might notice
Sources
- GeniaAir Appliance Interface installation and maintenance instructions ↗ · 8000043014_01 · page HPIM 7 8000043014_01 p.30 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026