There are code readers available on the web which will help you with this problem and anything going forward which can be had for about $200. It may be a wise investment as you are considering a scan from a Mercedes capable tool and that would cover half the price of a tool of your own. There are several threads on this forum in reference to scan tools which work into the Mercedes codes if you scan the car as a Mercedes SLK with the r170 frame. I myself use a Foxwell and it has done a okay job on the Crossfire as well as a 2005 CLK 500 I also own.