In this paper, structural analysis is used to design sensor network for actuator fault diagnosis in vehicle active suspension. The system consists of a full car model and the dynamics of the four force actuators. Being of large dimension, the system is decomposed into five interconnected subsystems. In addition to the control input, subsystems are subjected to road disturbances and to external inputs produced by the interconnections. The number and the location of sensors to be used are then determined for each subsystem.