To find it precisely, you'll need:
* A workshop manual: This is the best resource. It will have detailed diagrams and specifications.
* Access to the engine bay: You might need to remove some plastic covers or other parts for better visibility.
Important Note: Accessing this sensor often involves working with high-pressure fuel lines. Exercise extreme caution as fuel under pressure can cause serious injury. If you're not comfortable working on this system yourself, take it to a qualified Mercedes-Benz mechanic. Improper handling could result in a fuel leak and fire hazard.