An air guide is disclosed for a bonnet-covered engine bay of a goods vehicles, in particular agricultural tractors, where under the bonnet are located a combustion engine (1), components under high thermal load and low thermal load, and a fan which generates an air flow which is directed through air guide ducts past the combustion engine into the open. As the air flow from the fan heats up greatly on the combustion engine, there is a risk of a deterioration in the functioning of heat-sensitive components exposed to the air flow. To eliminate this risk, on both sides of the combustion engine (1) in the area of the components (4, 5, 6, 7) under high thermal load, between the combustion engine (1) and a side part (3) of the bonnet in a plane lying substantially parallel to the side part of the bonnet or combustion engine (1), is arranged an air guide element (11) which divides the air flow from the fan into an air flow (12) between the engine and the guide element (11) over the components (4, 5, 6, 7) under high thermal load and at least one air flow (13,14) between the guide element (11) and the side part (3) of the bonnet over the components (8, 9) under low thermal load.