I noticed that both the left and right side C-pillar trim pieces on my 2015 F56 have vertical hairline cracks (about 1 inch long). I'm not sure what caused them.

Has anyone else seen this or know how to replace them?

I found the parts needed (51137300013 and 51137300014) but have not figured out how to swap new for old.

 

Open the hatch and use a pry tool to pop it off. I believe there are 3 tabs - top, middle, and bottom.

 

Do you have a picture. Should be under warranty if not caused by being hit by something.

 

I'll try to post some pictures when I get a chance

I don't know what caused them both to crack - I don't see any signs of someone hitting the car. My best guess is my driving through a deep pothole on Friday. I noticed the cracks Saturday.

 

Just happened to my 2014 MCS on driver's side. Must be some stress on the way it's snapped in place, I guess. Going to ask the dealer about it.

 

Here is what they look like on the back side. Looks like they just cup around the corner seal and snap in.

51137300013 and 51137300014

 

I think you are right - they are held in place by the snaps. But I also think the leading edge must slide in under the stationary side window, and the top and bottom must slide beneath the roof molding and belt-line molding, respectively. I am not certain whether the C-pillar covers can be swapped without removing the various other trim parts.