In this case leave the AIRCRAFT.CFG intact.
The change must applied to the lamp itself - to the XML gauge.
The XML gauges are "zipped" in the XB17G.CAB file located in the B17's PANEL folder. You have to extract "Carb Filter OFF.XML" gauge/file, open it in Notepad, change "0" tp "1" in mentioned line and pack the file back into the CAB.
Now you are entiteld to call yourself the XML gauge programmer
The brakets and quotation marks must be there as they are the part of the syntax.
PS. Make a backup of the CAB first.