Hey! I’ve got a 2012 Civic SI that I just replaced the CMC and slave cylinder in. I believe that I’m getting air in through the 17mm press fitting on the CMC body where the hard line connects. There is a small square body o ring in there. The fitting has a little bit of wiggle room. Is this normal or do I need a new o ring for the fitting? I circled it below. Thank you!!

 

If it is a bad O-ring, fluid would be coming OUT... it would not draw air in. If it is out of the car, replace it with the non-dampened one from the '01-05 Civic EX chassis. You will be much happier.