In a method for adjusting a vehicle-mounted radar sensor having three radar lobes, which are emitted in a fan-shaped manner, one of which is a central lobe, and the other two are lateral lobes extending at the same angle, a reflector plate disposed at a distance from the vehicle and perpendicular to the vehicle longitudinal axis is pivoted about a vertical axis. The deviation of the reflector's position angle from an ideal position is determined. The ideal position is one in which the two lateral radar lobes produce at least a substantially identical reflection signal. The radar sensor is subsequently pivoted by a correction angle, which is equal to the deviation of the reflector plate's position angle, but in the opposite direction.