Just had my next service scheduled for my '17 c43 and it quotes the same campaign item: CAMPAIGN: SOFTWARE UPDATE OF POWERTRAIN CONTROL UNIT.
Found some documentation online from MBUSA about a campaign from march 22 - Campaign No. 21P5498710 that calls out 2015-2018 C-Class and GLC-Class (205 and 253 platform) vehicles - "It is possible that the next maintenance interval is displayed to the user as a negative distance reading in the instrument cluster."
Some other thread on the Mercedes US forum claims it changed the characteristics of pop and bangs on his c63 making it quieter, not sure if this is to believed in...
New Powertrain Control Unit (PTCU) Software - 21P5498710 - MBWorld.org Forums
Anyone with C or GLC (43 or 63 preferably) that had this update done already and could comment if it changed anything as to the behavior of the powertrain itself or is it indeed only some fix for maintenance interval readings?
thanks