Using Generic Scan Tool
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 Mercedes-Benz ML320, 2002 Mercedes-Benz E320, 2002 Mercedes-Benz CLK320, 2001 Mercedes-Benz ML320, and 2001 Mercedes-Benz E320. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition off. Connect generic scan tool to diagnostic connector located under left side of dashboard. See Fig 1. Turn ignition on. Follow tool manufacturer's instructions for reading fault codes. If no fault codes are present, but vehicle is experiencing a problem, go to TROUBLE SHOOTING - NO CODES (ENGINE 112) article.