Dim Cpt As Integer
Dim Feuilles() As Variant
Feuilles = Array("M1", "M2", "M3", "IZ", "CH", "ME", "CHEA")
For Cpt = 0 To UBound(Feuilles)
With Sheets(Feuilles(Cpt))
.Range("A1:S" & .Range("A65536").End(xlUp).Row).Sort _
Key1:=.Range("S1"), Order1:=xlAscending, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom
End With
Next Cpt