I installed the MMW header / S-pipe combo with a 2.5" Dezod exhaust lat month and have been in the process of making slight improvements to it. Since installing them, I replaced the 3" in/out (yes, 3") muffler with a 2.5" in/out magnaflow so it didn't sound so farty, and added a 2.5" in/out high flow Catco catalytic converter to clear up some smog.

Since then one of the catalysts broke apart in the cat for some reason and was rattling around terribly, so I had the exhaust shop bust it up the rest of the way and remove that side, leaving just the outlet catalyst. Another issue I ran into was the 2-bolt flange connecting the midpipe to the s-pipe was leaking, even with the gasket I installed. Every attempt I had made to line everything up perfectly still left me with an exhaust leak. One one occasion, after I had lined it up for the 3rd time I think, I took it onto the freeway and really gunned it (2am by that time and a very clear freeway ) and I got a CEL. I quickly brought it back home, unbolted the negative terminal and left it that way overnight. Next day I bolted the negative terminal, drove around, and no CEL. I drove CEL free for about 2 weeks.

The other day, completely fed up with the audibly noticeable exhaust leak from that flange, I got under there again and used 700 degree copper silicone RTV sealant to close up the gap between the gasket and the flanges, and I bought M12 bolts, nuts, washers and lock washers to replace the M10 stuff I had used, so lining eveything up was quite easy compared to before. I was quite pleased to discover NO LEAK!!! :D Soon after, I took the car on the freeway (again really late at night and no people on the road) and revved it and gunned it. I got another CEL, came home quickly, unbolted the negative terminal for 15min and bolted it back on. I drove the next day and when accelerating quickly on an onramp the CEL came on. I unbolted the terminal again for 1hr and rebolted it. Until now, no CEL.

Aside from sharing my exhaust woes and successes, I wanted to ask if my CEL might be related to the unbolting and rebolting of my exhaust. And my other question is, does the length of time you leave the negative terminal unbolted have any effect on erasing a CEL? Thanks.