The M2W box is just emulating an open fuse. Which should not throw a code, if it did there would be hundreds if not thousands of us with our check engine lights on. I have been running my Exhaust Commander for about 1300 miles now.
Sounds like when you were getting on it after taking it easy for the break in period you dislodged some soot onto a sensor. Just my guess,,, I bet another round of "spirited" driving would probably clear it
