as far as i know the scangauge will not ignore any codes, if it comes back right after you clear it, it will come back on

not sure about the loop... ill have to check it

i think normal ign is 16 at idle

for your mpg.. program a code to show your current trip mpg, it will get rid of that annoying 9999mpg that pops up when you let off or the 4mpg that shows up when you get on the gas

pm me if you have any questions about making your own gauges, ive made a few of my own