For M-Class (W164) vehicles:
1. Open the hinged cover by pulling on the handle under the vehicle.
2. The filter is located underneath the cover, under a black plastic cover with red label with the word “Kraftstofffilter” (fuel filter).
3. Remove the black plastic cover and install the new fuel filter. Remember that fuel filters should be replaced every 20,000 miles.
For R-Class (W251) vehicles:
1. Open the hood.
2. The fuel filter is located on the passenger side of the engine compartment, near the firewall.
3. It is a cylindrical object with a black plastic cover.
4. Remove the black plastic cover and install the new fuel filter. Fuel filters should be replaced every 20,000 miles.
