Mercedes-Benz vehicles use a two-part hood latch system. The initial release of the latch handle is accomplished by pulling a release lever within the vehicle. A second handle, the hood catch handle, is located externally and releases the hood itself. Problems with the system can be rectified by following some simple steps.
Pull the internal release lever again if you can't open the bonnet with the external hood catch handle. The external hood catch handle won't work unless the interior release lever is pulled first. You can find the interior lever to the left of the steering wheel, just above the foot well.
Pull the hood catch handle outward from the radiator grille if the hood latch won't open the bonnet. You'll see the hood catch handle in the right half of the radiator a few louvres down from the top. Pull it outward as far as it will go and lift the bonnet from underneath. On many Mercedes vehicles, the radiator grille is part of the hood, so grasp the hood below the radiator grille for a good grip.
If the latch won't catch, close the bonnet by letting it drop from about 8 inches. The hood needs a firm, gravity-driven closing for the hood latch to work properly. If the hood is raised slightly, the latch isn't engaged. Try closing the hood again with more force.
Lift the bonnet by the bonnet or radiator grille and not the hood catch handle. The catch handle isn't designed to lift the bonnet and may become damaged if you use it to do so.
The system is designed to be used when the vehicle is stopped, because air flow passing under the hood could force the hood open. This could cause the bonnet to become loose and airborne.