I know this thread is somewhat dated, but before I left for China business trip a week ago, I took the coupe on a few errands. It had been sitting quite a bit over the winter season. Then when it warmed up a bit, I took the headliner out to have it recovered. Right after I re-installed the headliner, I cleaned up the car (prep for CAA8 trip) and took it for a spin.

I noticed I had a "spongy" brake pedal and never had this before. I've got Goodridge SS brake hoses all around (installed last fall), installed "brake bleeder" screws on all wheel cylinders, & filled the system with Pentosin brake fluid. Master Cylinder still shows full with clear brake fluid. Right after the brake line swap & brake system bleed/flush, the brake pedal was rock solid. Will leave for CAA8 on Saturday, 06/24, & wondering whether I need to change out a Master Cylinder. Irritating that this flared up with car just sitting there. I didn't run any codes before I left, and can do that easily when I return on 06/22. I'll have a full day to do some work before leaving, just wanted to hear folks suggestions on most likely cause of condition. But based on the searches I've conducted, looks like an internal leak in the Master Cylinder is most likely cause.

Any & all feedback is appreciated.