SD Connect C4 “Internal Error CSD DLL not found” Posted on June 20, 2019 by wp-admin Can somebody help me? I bought the Mercedes-Benz SD Connect C4 diagnostic system. Then the first cat (real car) I hooked up to this is what came up. Solution shared by customer: I fixed it. Updated firmware in MB SD C4 interface and new key. Related posts: How to Solve MB SD Connect C4 Update Error Report? SD Connect C4 – MUST READ BEFORE YOU BUY MB SD Connect C4 computerlaptop issue (solved) Review MB STAR C3 XENTRYDAS Windows 10