DTC code P0441 is almost always a faulty evap purge valve(regeneration valve in MB literature). It is very common for this model and the valve sits on the frame rail on the left front fender right next to the washer tank. It is a black solenoid valve that has two large vacuum lines going to it on each side and in white lettering it will say "MOT" with an arrow indicating flow. When they are woorking properly they "pulse" and are somewhat noisy, like a ticking sound. When they fail they usually stick closed and don't allow the evap pressures from the tank to release into the intake manifold. The valve is fairly cheap and take about 3 seconds to replace.