2003 Boxster coolent leak
 

After sitting in the garage for a couple of weeks I took my Boxster out. When I returned to the garage I noticed fluid leaking on the floor of the garage. It came from the area of the rear passenger side of the car at the rear tire. I opened the rear trunk a noticed liquid around the cap for the coolant. The cap did not seem loose, though I had the oil changed a couple of weeks before. Could the coolant have backed up through the cap? If so, why? Or could there be another problem?

remove the inner cover at the trunk and inspect the coolant reservoir for any cracks.
this is a very common issue in the boxster.

Thanks, will check it. I suspect it is the filler cap right now.

Check that you have the latest version of the coolant reservoir cap. The early ones are renowned for leaking.