Bonjour,
Si j'ai compris, si la cellule G200 n'est pas vide, l'onglet est en jaune
A tester.
Private Sub Workbook_SheetSelectionChange(ByVal Sh As Object, ByVal Target As Range)
Dim RngPlageVal As Range, RngCel As Range
Dim Valid As Integer, NonValid As Integer
Set RngPlageVal = Range("G200")
For Each RngCel In RngPlageVal
If RngCel.Value <> "" Then NonValid = NonValid + 1
Next
If NonValid = 1 Then
ActiveSheet.Tab.ColorIndex = 6 'jaune
Else
ActiveSheet.Tab.ColorIndex = 2 'blanc
End If
End Sub