Code 6 at DM simply means a fault has been from the ISC system that could effect emmissions standards and that info has been sent over to the DM.
Now you want to go over to the EA/CC module and see exactly what fault/s have been detected.
It could be as simple as a cable adjustment to a bad ISC or wire harness.
You can get that info at connector #14 on the DM box with a simple Led/Sw tool...

http://members.aol.com/ajdalton7/ledtool.jpg