Vaillant · Heat pumps · Vaillant aroTHERM plus with uniTOWER plus
M.203Connection fault: Display not recognised
Name in the manufacturer's documentation (service manual): Connection fault: Display not recognised
[1]
In plain words (editorial)
The display is not recognised – it is defective or not connected.
When to call a service technician: Contact a competent heating engineer (installer or Vaillant customer service).
✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.
For technicians
Steps given by the manufacturer (source text)
⚠ Work on refrigerant circuits, mains electricity and PV DC wiring is for qualified technicians only.
The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →
Sources
Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.
- [1] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified
M.203
- [2] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified
Display defective
- [3] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified
Display not connected
- [4] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified
Check the quality of the plug contact on the PCB and on the wiring har- ness
- [5] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified
Replace the display, if required