This code is sufficient:

Sub M_snb()
   c00 = "03_PROJECTS\AUTOS\" & [B1] & "_" & [B11] & "\Test_Info\Pics\Service_comments\Printouts"
   c01 = "\TP_" & [B11] & ".xlsb"
   If Dir("G:\" & c00, 16) = "" Then CreateObject("shell.application").Namespace("G:").NewFolder c00
  
   If Dir("G:\" & c00 & c01) = "" Then ThisWorkbook.SaveAs "G:\" & c00 & c01, 50
End Sub