Is this something to be worried about?
http://i.imgur.com/Hbtrwl.jpg

I did change one bulb in the rear left cluster about a week ago so it's maybe related? All light are working as they are supposed to, though...

If teh bulb you replaced is of the correct rating and they're all working then stop worrying!

As all the fault codes refer to the left rear lights, there could be an intermittent problem with the left rear earthing point.

Thanks to both! For now I cleared the error and will check soon if anything changes.