I had 2 errors come up related to tail lamps failure. Sockets tend to corrode, not a great design.. For the brake lights a replacement kit is available. Mercedes don’t seem to supply sockets on their own, but there is a simple solution. Look up on eBay ‘P21W sockets’ from BMW (white in colour). Then replace the contacts on the Mercedes socket with the copper contacts (which are better) and job done!