200 on a Vaillant aroTHERM plus: Comfort protection (limp home) mode code 200 - Sensor fault: Temp. air inlet
Short answer
On a Vaillant heat pump, 200 means: Comfort protection (limp home) mode code 200 - Sensor fault: Temp. 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: Comfort protection (limp home) mode code 200 - Sensor fault: Temp. air inlet.
Part involved: Air inlet temperature sensor (outdoor unit).
Likely causes:
- Air inlet (outdoor unit) temperature sensor fault; operation still possible using the functional outdoor temperature sensor.
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.
Manual reset: engineer replaces sensor; message persists after reset while fault present.
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). The product keeps running with reduced comfort; consult a competent person (operating instructions).
What the engineer will check
- Replace the air inlet sensor; read fault memory to identify the defective component (after reset the fault message is shown first, then limp home/comfort protection).
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
What owners and engineers report
18 owner and engineer reports mention this.
- Poor efficiency (low COP/SCOP) on the aroTHERM plus (VWL ../6 A): 18 reports
Sources
- uniTOWER (VIH QW 190/6 E) operating, installation and maintenance instructions ↗ · 0020291525_05 · page uniTOWER 0020291525_05 p.59 (Appendix I); split hydraulic station 0020257319_05 p.56 (Appendix H); VWZ MEH 97/6 0020291544_03 p.51 (Appendix H) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026