This paper deals with sensor fault diagnosis for a battery management system (BMS). The diagnosis procedure consists on the detection and isolation of sensor faults. A new battery pack design, composed by the cells and sensors, is introduced. Three sensors are considered: voltage, current and temperature. The algorithms are simple and efficient, even for multiple faults, so as to be low-cost from computation and power point of view. Examples are developed during the paper to show the effectiveness of the technique.