mercedessource.com This tool can help diagnose a number of common problems on not only diesel but also gasoline Mercedes Benz. If your diesel won't shut-off this tool with help you find the cause. If you door locks won't work then this is a must have. If you are not sure your engine's vacuum pump to producing the proper amount of vacuum these this tool with confirm. Every 220D 240D 300D 300CD 300TD 300SD 300SDL 190D 350SD 350SDL owner who does his own maintenance with eventually need to get his hands of a hand pump vacuum tester.